Common Knowledge

In TV, there are some things that everyone knows... Well, sorta. As it turns out, people as a whole know less than they think they do. Casual viewers of a series will often come away with their fair share of mistakes. Such fallacies are often used by Real True Fans™ as a yardstick of the difference between themselves and the masses.

All the same, these notions can be so firmly entrenched in the public zeitgeist that they can force their way into adaptations, much to the annoyance of the aforementioned Real True Fans™.

Named for a Saturday Night Live game show sketch in which the questions were selected by experts reflecting things all high school seniors should know, and the answers were selected from a survey of high school seniors (that is, they were wrong).

Subtropes are Title Confusion, I Am Not Shazam, Beam Me Up, Scotty, and Refrain From Assuming. May result from or lead to Lost in Imitation, or from any of the subtropes under Time Marches On. When left unchecked, it can lead to Media Research Failure, Analogy Backfire and Never Live It Down. See also Reality Is Unrealistic, The Coconut Effect, Dead Unicorn Trope, and Everybody Knows That.

Anime/Manga

 * The entire genre has a few:
 * What was the first anime? Astro Boy, of course! All fans of the genre know that! Except, it wasn't. While the 1963 anime was groundbreaking in many ways and set the standard for the genre for decades to come, it is no more the first anime than Gundam was the first anime to have Humungous Mecha. What was the first? Well, depends a lot how you define "anime". If one defines it as "Japanese animation", there was a short three-second short called Kazato Sashin that features a boy drawing Kanji and bowing. This was believed to have come from way back in 1907, predating Astro Boy by over five decades.
 * Dragon Ball is the most popular manga, right? Eh, wrong, although it is one of the most popular. The title usually number one (as far as sales and readership go) is usually One Piece, which often ranks as the third best-selling and critically acclaimed popular comic book in the world after Superman and Batman.
 * Most anime fans also claim anime is more accepted in Japan than it is in the west. It is not. Japan regards it as a juvenile, informal type of entertainment much the same way cartoons are viewed in general, and they have just as many Moral Guardian types as everyone else.
 * Space Runaway Ideon's famous ending where it "blows up the universe" never happened. Granted it killed all of humanity (both Terrans and Buff Clan), destroyed hundreds of planets, spawned thousand of meteors that blew up the Earth, destroyed Saturn's rings, and took out much the Milky Way Galaxy, but the rest of the universe is just fine. This was largely a piece of Memetic Mutation as "Ideon blows up the universe" sounds a lot funnier.
 * In the other movie, it is stated by one of the Buff Clan protagonists such. This can be dismissed as hyperbolic enthusiasm, however.
 * Not in Super Robot Wars; Ideon snuffs out all life save for Keisar Ephes.
 * Similarly, the main twist of Haruhi Suzumiya manages to be this and All There Is to Know About "The Crying Game" at the same time. Namely all the people that specifically think/say "Haruhi is God", when all the audience or any of the characters in the story know is that she's some sort of Reality Warper, and being "God" is just one theory which is stated to not be particularly likely.
 * In fact it's Koizumi who makes the God claim, and we know that a lot of what he says is a lie.
 * He also says that he's working under that assumption mostly because it's the worst-case scenario.
 * Some individuals believe that in Jimmy Kudo in Case Closed is seventeen years old at the beginning of the series. This is largely due to the Wikipedia article about Case Closed. However, Jimmy is actually sixteen at the beginning; Jimmy almost inadvertently tells Rachel his real age in Volume 1, Chapter 2, Page 18, before remembering that his body is shrunken and correcting himself.
 * When people talk about how Ash Ketchum of Pokémon doesn't follow the rules of the game, many people point back to his battle with Brock in the fifth episode, and how Ash somehow won against a Ground-type with an Electric type. What most people do not remember is that in the very first battle between Ash and Brock, Ash lost badly because of the type disadvantage. In fact, because of that loss Ash went through a process to supercharge Pikachu to even be able to damage Brock's weaker Geodude (which, incidentally, Pikachu did by hitting the ground underneath Geodude). But it gets better; some people do recall the stated reason why Pikachu won; sprinklers had activated and doused Brock's Onix. What most people don't remember however, is why the sprinklers turned on. It was due to the fires caused from Pikachu's earlier supercharged attacks, not Pikachu's attacks themselves. Hell, the sprinklers went on after Pikachu had taken heavy damage from a Bind move by Onix! And the final nail in the coffin here? Ash did not accept his victory. He pointed out that he only defeated Onix due to the sprinklers and stated that he wanted a fair match. He then promptly leaves, without the badge.
 * And even though Ash does get the badge a couple of minutes later without another rematch, it's only after a long discussion with Brock that he does so.
 * Many people think that in the infamous banned episode that caused seizures, Porygon was the culprit, when it was actually PIKACHU who was in the scene that caused the seizures.
 * For the record, the scene runs as follows: Everybody is escaping on Porygon's back when some anti-virus missiles (launched by Joy earlier in the episode) start to hone in on them. Pikachu jumps out and destroys the missiles, causing the flashes (which appeared earlier in smaller bursts).
 * Each region has 8 gyms, and you need every gym badge to get to the Pokémon League, right? Except in the first season, it doesn't work that way. In Kanto at least, the actual number of gyms is much higher and always increasing, you just only need 8 of their badges to pass. The show displays this when Gary shows up in Viridian City to battle against Mewtwo. At the time, he had ten badges from the Kanto region, and wanted another.
 * For that matter, you do not need to earn the badges in any specific order in the anime, contrary to popular belief, and Gyms aren't ranked by "level" or any such nonsense - in fact, multiple characters other than Ash have display their badges, and at times they have various badges Ash also obtained, yet display them in their Badge Case a completely different order to him (most line them up in the order they get them).
 * Every region other than Johto and the anime-only Orange Islands has been shown to have more than eight gyms.
 * Similarly, many people like to complain about how the Duelist Kingdom arc of Yu-Gi-Oh! don't follow the rules, either; that's because at that time, the game was a Plot Tumor that basically had no rules to follow, and needed to be made up wholesale (there's even an obscure version of the game made by Bandai that follows a much different set of rules than the OCG/TCG). In fact, Pegasus even states that "there would be new rule changes" at the beginning of the arc, meaning we don't know exactly how the rules prior to that arc was any different. That being said, the anime didn't start following the OCG/TCG rules until the Battle City arc, when Kaiba instated them, and the rules weren't fully solidified until GX.
 * That being said, a lot of the crazy things that happen in that arc do have some merit in regards to the game; for instance, the "field power bonus" correlates to the real game's concept of a Field Spell, and the former Trope Namer of "New Rules as the Plot Demands'' could've actually worked in the real game, given the effect of Catapult Turtle and the progress of the duel (and the obscenely low LP the players start out with, at the time).
 * Well, if you just use catapult turtle to sacrifice gaia the dragon champion and deal 1300 LP worth of damage and win due to total LP depletion then that would is possible. As for everything else that happened in that scenario, not so much.
 * The Shadow Realm. It is not a place of eternal torment, or an analog to death, and there is actually a place called "the Shadow Realm" in the Japanese anime; it's actually a pocket dimension created around the players of a Shadow Game to enforce the rules of the game and prevent outsiders from interfering, or the players from leaving the game until there is a winner.
 * According to most people, Shana of Shakugan no Shana and Louise of Zero no Tsukaima are equals personality wise. Except they're not, at all. Shana starts rather rough but becomes nicer, less Tsundere and more Defrosting Ice Queen (this is technically the original definition of a tsundere, but that's neither here nor there). At points she's more of a Type 2 Tsundere, but in general she veers towards nice. In the other hand, Louise is a Type 1 tsundere through and through, and a rather harsh one at that (But she has her sweet moments too, mind). Yet despite the obvious disparity, people will treat them as the same. In all fairness, this is more J.C.Staff's fault, who after the success of Shakugan no Shana decided to play Louise's physical similarities by giving her Shana's voice, despite being completely different kind of tsunderes, as said. It's even better when Nagi and Taiga are thrown on the mix: While Taiga is indeed a lot like Shana (Only not an Action Girl because her show isn't about fighting), Nagi is a regular Type 2 Tsundere as well as a Gamer Chick and a Otaku Surrogate; once again, little to do with Shana and nothing to do with Louise. Yet still all four are treated as the exact same character, and all because they're all long-haired, flat-chested, have Zettai Ryouiki and share a voice actress!
 * In regards to the Digimon series many people will refer to fanfics that are supposed to be a sequel to 02 (or sometimes even Tamers) as "Digimon (Adventure) 03". While technically correct, it's not right for the reason people think it is: "02" in "Digimon Adventure 02" refers to the year in which the story takes place (2002; Adventure took place in 1999, three years before); thus "03" would actually be a story in 2003.
 * The fact that Ranma and Genma disdain weaponry is common knowledge. In fact, Ranma is shown to be expert with staff, spear, nunchaku and there are some official publicity pieces by Takahashi showing him performing routines with a Jian (the Chinese sword of nobility).
 * In Naruto it is common knowledge that the Mist village, during its "Bloody Mist" days at least, had a policy of exterminating bloodline users, and that Madara was the Man Behind the Man in this village and orchestrated these genocides because he deemed them inferior to the Uchiha bloodline. Neither of these things are true- bloodline users were persecuted, yes, but by ordinary people in the Water country and elsewhere, not by the Hidden Mist village (which is only part of the Land of Water as its ninja village); and the idea that Madara has a problem with non-Uchiha users is based on a popular fan theory, due to his Motive Rant to Sasuke where he blames the Senju clan for persecuting and betraying the Uchiha clan, even though it was largely his fault, and tells Sasuke about how superior the Uchiha were. Fans put two and two together and assumed he was an Uchiha supremacist, even though much of his rant was mixed in with Blatant Lies and was transparantly designed to mess with Sasuke's mind. Haku's mother was killed by her father, and Kimmimaro's clan was killed by the Mist only when they attacked it, which they only did because they were a clan of Stupid Evil Blood Knights. Madara has never shown a flicker of hatred for bloodlines in general and the Mist, being a Hidden Ninja Village, most probably had a policy of collecting them- the current Mizukage is actually a user herself (twice over). This one is quite egrarious as even a lot of Real True Fans actually believe this. The fact that does not help this.
 * Iwa is claimed to hate Minato and will kill anytime even related to him despite the fact that he's dead. It's usually the reason why Naruto's parentage is hidden. The Fourth Hokage has never even been mentioned by any Iwa Shinobi. What Iwa had was a "flee on sight" order regarding Minato during the last Shinobi War (when Iwa and Konoha were on opposing sides), because Minato was too powerful for any of them to stand a chance against, with the possible exception of the Tsuchikage. This doesn't indicate any grudge against him, just a tactical judgement that it's never wise to fight the One-Man Army on his own terms.
 * Kurenai has been claimed to have been in Hinata's life since she was a child. However multiple (anime-only) flashbacks say otherwise.
 * In Gundam Seed Destiny, the Nazca carrying the Neutron Stampede is commonly assumed to be called the Marie Curie. Except that it's not; no name is given in-series, and the origin of the name is from a fanfic called Birds of a Feather.

Comic Books

 * As far as most folks know, Spider-Man's chief superpower is his ability to shoot webs. Unfortunately, this is not among his super powers at all. Webshooting was instead the ability of a device Peter Parker had built for himself. Spider-Man's actual super powers are his ability to cling to walls, his "spider sense", superhuman strength and agility. It's only in the movies that he gained the power to shoot webs naturally, although this did make its way to the comics, briefly.
 * Speaking of Spidey, remember, it's not Spider Man, or Spiderman. It's Spider-Man! Don't forget that hyphen!
 * X-Men has several misconceptions, mostly due to Fox's "realistic" depiction of the characters:
 * Some mistake Wolverine's adamantium claws as his mutant power. His mutant power is actually a very powerful Healing Factor (as well as claws made of bone). All of his other "natural" powers (such as his heightened senses) stem from this. As with the rest of his skeleton the military grafted him adamantium claws to him specifically because he had the regeneration powers to survive the process.
 * It gets worse. Until Barry Smith wrote Weapon X, it was generally assumed (and described as such in early editions of the Official Handbook of the Marvel Universe) that the claws were bionic, & implanted with the rest of the adamantium.
 * Until Magneto ripped the adamantium out of Wolverine (eventually it was restored), even Wolverine himself believed the claws were implants. Due to memory implants and induced amnesia, he knew nothing about his own life prior to the Weapon X program.
 * And in the early stories the claws were telescoping, and contained in his gloves!
 * Similarly to Spider-Man, several casual X-Men fans complained about Rogue not having her flight and invulnerability powers in the movies. This is because the Superman powerset isn't rightfully Rogue's in the comics, either: Rogue semi-permanently stole those powers from Ms. Marvel off-panel prior to her first canon appearance (and has since lost and replaced them with Sunfire's).
 * Everybody knows that Cyclops "shoots lasers from his eyes", which is not true; he projects beams of concussive force, which (unlike lasers) don't radiate heat. Also, many people assume that his inability to control his optic blasts is an inherent curse of his mutant powers, which is also untrue; it's because of head trauma that he suffered after jumping out of an airplane as a child. note  And everybody knows that he's little more than a boring Standardized Leader who's good at barking orders at his teammates, but can't hold a candle to them in combat; except he's been established for years as a skilled martial artist and tactician, he's beaten supervillains like Apocalypse and Mr. Sinister in single combat (as well as entire armies of Sentinels), and one memorable story had him battling all of his teammates at once and winning. Much of this comes from the cartoon, where he generally came across as kinda incompetent.
 * Everybody knows that the classic storyline The Dark Phoenix Saga was all about Jean Grey pulling a Face Heel Turn and becoming the villainous Dark Phoenix, then committing a long slew of atrocities before dying. Except it wasn't. Firstly, Jean didn't become the Phoenix; the Phoenix was an alien entity that possessed her after choosing her as its vessel, and slowly went mad with power as it got used to life with a human host. Secondly, it has since been established (thanks to a Retcon) that the character who murdered multiple people in that story was not Jean; rather, the Phoenix temporarily replaced her and assumed her bodily form after Jean was seemingly killed in a spaceship crash. Of course, since most of this didn't become clear until years after the story was published (and a later story did have Jean becoming the Phoenix), many people find it hard to keep the details straight.
 * Despite fan-shipping and a few adaptations that might lead one to assume otherwise, Wolverine has never been more than a Hopeless Suitor (if even that) to Jean. His crush on her has never become an actual relationship; the closest they ever came to "getting together" was when they kissed in one story because they both thought they were about to die. That's it.
 * It's often assumed that being a mutant (as in, "homo superior") is a prerequisite for being a team member, ally, or villain in an X-Men comic (unless of course you're a human who exhibits Fantastic Racism or Moira MacTaggert), and that every long-running character that's part of the mythos is one. While the vast majority of X-related characters are indeed mutants, there are also a surprising amount of non-mutants who've been involved (granted, with the sheer amount of characters the mythos accompanies, it was inevitable there would be some exceptions). This includes Juggernaut (magically enhanced human, Longshot and Spiral (interdimensional beings), Warlock, Lockheed, and Hepzibah (aliens), Fantomex, Bastion, and Lady Deathstrike (cyborgs), several members of the X-Club (normal human scientists), Mimic, Cloak & Dagger, Mister Sinister (human mutates), Doop (artificial being), the Children of the Vault (super-evolved humans), Captain Britain (normal human with mystical weapons), Shatterstar (time traveler from the future), and Omega Sentinel (human-sentinel hybrid). Omega Sentinel is particularly notable, considering she was originally programmed as a Sentinel to kill mutants; that's about as un-mutant as you can get. It causes a bit of Fridge Brilliance; seeing as their goal is to create equality between mutant and humankind, it'd be rather hypocritical if the X-Men didn't allow non-mutants into their ranks.
 * Once upon a time, this was uncommon knowledge, but nowadays, it's common knowledge that Batman, at the time of his creation in The Golden Age of Comic Books, was a much "darker" character than he became in the '50s and '60s. Which is true to a point, but it wasn't long at all before the character was made Lighter and Softer. As Eisner-nominated comics journalist and professional Batmanologist Chris Sims noted, "Sure, he might’ve fought vampires and carried a gun for like three issues, but by the end of that first year, it was pretty much all cat-wrestling and trips to Storybook Land."
 * Barry Allen snapped Professor Zoom's neck during his wedding to Fiona Webb, his second wife, not Iris West who had already been dead for quite some time in the comics and real life by the time of the story. Since Barry and Iris are a classic comic OTP most people are totally unaware of the fact that Barry had other women in his life.
 * While everyone thinks of Clark Kent changing into his Superman clothes in a Phone Booth, the truth is that he's hardly ever done so in the actual comics. He does, however, do so in the Superman Theatrical Cartoons, which, incidentally, was also where Superman first truly "flew".
 * It's widely known that Wonder Woman wore a skirt in the Golden Age. And it's true... sort of. In her very first story (All-Star Comics #8), she wears what appears to be a skirt, but it was immediately changed to culottes—a style popular among athletic young women at the time, and one that resembles a skirt, but is actually shorts. And even those shorts evolved quickly into tight shorts that lost the "skirt" look entirely. Nevertheless, whenever a modern artist wants to evoke a "Golden Age Wonder Woman" look, she's almost invariably drawn wearing a skirt.

Film

 * Zombie Apocalypse movies in general. Everybody 'knows' that zombies eat brains. This only happened in one series of films, Return of the Living Dead. In every single non-parody portrayal of a Zombie Apocalypse after that, zombies merely want your flesh, not your brain.
 * Star Wars: For the last freaking time Darth Vader did not use the Death Star to blow up Alderaan; Grand Moff Tarkin did. Vader was present at the time, and it's not like he cared or anything, but it's pretty annoying when people can't remember which person blew up an entire planet.
 * And, for the record, there are a number of different sources for the plans for the first Death Star in the Expanded Universe, all of which are mutually exclusive—unless you accept the Hand Wave that they were each part of the plans—but none of them conflict with a statement about Bothans getting them in the movies. That was the Second Death Star.
 * People Rooting for the Empire say the Clone Troopers were Jedi slaves. While they were ordered by a Jedi, it was on behalf of the Republic, from whom both Troopers and Jedi take orders. The Republic led by Chancellor (and future Emperor) Palpatine, without whom there would never have been a war to need Clone Troopers or Jedi generals.
 * Many people also think that the Ewoks lived on Planet Endor, they actually lived on a moon of Endor (which is itself called Endor on occasions, adding to the confusion).
 * Inigo Montoya isn't the main character of The Princess Bride. While it may have been an Ensemble Cast, that title would have to go to Westley. It's an understandable mistake, given that "Hello. My Name Is Inigo Montoya. You Killed My Father. Prepare to Die," and "You Keep Using That Word" are repeated multiple times every day on internet forums.
 * Dr. Frankenstein's hunchbacked assistant in the first movie was named Fritz, not Igor. The closest thing Universal's Frankenstein movies ever came to having a character named Igor, was Ygor in the third and fourth movie. Ygor was not hunchbacked, and he was not Frankenstein's loyal servant. Rather, he was a schemer who wanted to reanimate the monster for his own personal gain. The idea that hunchbacked assistansts are typically named Igor was probably made popular by Mel Brooks' Affectionate Parody Young Frankenstein. The Other Wiki proposes the non-hunchbacked assistant Igor from House of Wax as another possible influence.
 * Of course, it's also fairly common knowledge that Frankenstein was the monster, when in fact Doctor Frankenstein created the monster.
 * The gruff, rough, and tough drill sergeant in Full Metal Jacket was verbally abusive to his men, but he got results. Those results were that.
 * People going on a trip by motorbike often reference Easy Rider, for the true spirit of the freedom-loving, all-American road-trip... forgetting.
 * Zeppo Marx is known as the fourth member of the Marx Brothers who added little to their movies besides singing sappy love songs. Actually, the only love song Zeppo sings in the Marx Brothers movies, not counting the Maurice Chevalier impersonation in Monkey Business, is "Everyone Says I Love You" in Horse Feathers.
 * He's actually the fifth member. The fourth member, Gummo, quit around World War I, long before their movie career.
 * The flying saucers in Plan 9 from Outer Space are commonly believed to have been pie tins or paper plates, to the point that it's tradition to throw paper plates around during screenings of it. In fact, they were children's flying saucer toys.
 * The James Bond series is the one where Bond manages to seduce the beautiful lady working for the baddies into helping him? This has happened precisely ONCE, in Goldfinger. Most of the rest of the time, the main Bond girl is either on his side from the start (Moonraker, For Your Eyes Only, Tomorrow Never Dies), an innocent caught up in the adventure (Dr. No, A View to a Kill, GoldenEye) or working with the villains but unaware of their true plans (From Russia with Love, Octopussy). Or they don't turn at all. Octopussy is the nearest example in that the title girl is a criminal, but while in league with the villains she is ignorant of their evil scheme, and is actually a target of it.
 * The misconception might actually be traced to another Bond film, Thunderball, the film immediately following Goldfinger. Fiona Volpe tells Bond that he's infamous for seducing "bad" girls and turning them to the side of good, and that it won't work on her. Bond, for his part, has already decided that he's dealing with a crazy ass bitch and seems to take her assumption - or her seriousness about it - as just another sign of her wackiness, and shrugs it off by saying "you can't win them all".
 * Another possible source of this misconception is that Bond is not above getting things he needs from other women (not necessarily the main Bond girls) through both seduction and trickery; if the seduced woman learns of the deception at all, it won't be until much later. Examples include Pola Ivanova from A View to a Kill and Corinne Dufour from Moonraker.
 * Jason from the Friday the 13 th series is sometimes depicted with a chainsaw. There is no movie in which he uses a chainsaw, the closest he got to that was when he used a limb trimmer in Part VII. It is actually Leatherface from The Texas Chainsaw Massacre who has a chainsaw as his primary weapon. Jason's primary weapon is a machete.
 * Even if they've never seen it, everybody knows that Brokeback Mountain is "the gay cowboy movie". Even though they were shepherds, not cowboys. And they were bisexual, not gay.
 * Quick, who directed The Nightmare Before Christmas? Easy, Tim Burton. Every fan knows that. Except, he didn't. He did design most of the characters and was co-producer, but the actual guy in the director's chair was Henry Selick, who would go on to direct animated movies like James and the Giant Peach and Coraline.

Literature

 * Frankenstein, which the public has unilaterally made the name of the monster, not its creator, and the monster usually is named Frankenstein in adaptations not striving for accuracy. This example falls squarely under I Am Not Shazam, but it's such a potent example that it merits mention here as well.
 * Even better, people typically believe that Victor Frankenstein is a doctor. In the original novel he does not have a doctorate of any sort, and is merely a medical student.
 * Almost everyone "knows" that the monster is a bumbling idiot who means no harm, even though he was actually very intelligent and self-aware in the novel.
 * And another one—everyone "knows" the monster was brought to life with lightning, or at least electricity. Except the novel specifically avoids saying how it was done. There is a mention of Victor Frankenstein being fascinated by the effects of a lightning strike earlier, but that's it.
 * And another one: everyone "knows" that the monster is pure evil from the beginning. Even many of the more faithful adaptations involves Victor narrowly escaping as it immediately assaults him. In the original, the monster tried very hard to be accepted and spent an entire winter caring secretly for a poor family. The rejection he faced everywhere he went led to his killing people.
 * Though if you want to get technical, the Monster could be called Frankenstein as well, if you take him to be essentially Victor's abandoned son as well as his creation. But thats a matter for another place.
 * The Monster was being referred to as "Frankenstein" almost immediately, while Mary Shelley was still alive and before the second edition came out in the 1830's. The Monster was named as "Frankenstein" in the program for a play version that came out in Shelley's life-time too, one she enjoyed. "Frankenstein" is a valid name for the Monster, by implied Word of God, so Common Knowledge is correct.
 * The tale of the Trojan Horse is usually attributed to Homer's The Iliad (or at least assumed to be related therein). In fact, the Trojan Horse incident appears in neither The Iliad nor its sequel The Odyssey—it merits only a brief mention in the latter, occurring between the events of the two poems. The lesson the story teaches us, "Beware of Greeks bearing gifts," which is also usually attributed to Homer, is actually a paraphrase of a quote (original quote was more like "I distrust Greeks, even when they do bring gifts") from Virgil's Aeneid, making this the mythological equivalent of Fanon. Of course, Oral Tradition doesn't really have any "true" authority, but Aeneid was written quite a while later and by a Roman.
 * The Aeneid also claims the Romans were descended from the survivors of Troy, so it wasn't exactly a friendly version of events. Half of it consists of the heroes cleaning up the messes the Greeks in the Odyssey left all over the Mediterranean, and generally making a point of facing the same challenges without getting all of their own men killed in the process.
 * The legend of the Achilles' Heel is also not in The Iliad, which implies that Achilles has ordinary vulnerabilities.
 * The title of 20,000 Leagues Under The Sea refers to the distance the sub travels, not the depth to which it goes. A "league" is a non-standardized measure of how far someone can walk in an hour. Verne used a metric league equal to 4 kilometres, so 20,000 leagues is 80,000 km (50,000 miles) which is over six times the diameter of the Earth, or twice its circumference. Additionally, if the "under the sea" didn't refer to where they were when traveling but how far under something they were it would imply they're not underwater, but rather under the ground beneath the ocean.
 * Couldn't find the video, but it is parodied hillariously in this transcript of a SNL sketch
 * Whenever a non-Harry Potter fan hears about Harry having romance in his life, it's assumed he'll be getting together with Hermione. Because she's the only female character non-fans have actually heard of. This is made all the more hilarious by the fact that Harry/Hermione shippers are considered a bit of a joke in the fandom due their insistence prior to the end of the series that the pairing would be reciprocated despite J. K. Rowling telegraphing Ron/Hermione about as obviously as possible.
 * A rather more squicky version can be seen with non-Star Wars fans (who are usually only aware of the first film) assuming any romance of Luke Skywalker is with Leia.
 * Back to Harry Potter, a lot of portrayals of new Hogwarts students other than Harry entering the school have the new character getting their acceptance letter on their eleventh birthday exactly, forgetting that Harry was sent hundreds before his birthday; he just didn't open it until Hagrid gave him it after several days of the Dursleys trying to escape them.
 * The Strange Case of Doctor Jekyll and Mr. Hyde: Hyde was Jekyll's evil, unrestrained side, yes, but Jekyll was not his own good side. It is specifically pointed out in the book that Jekyll is both good and evil, a fact nearly every single story, parody, or adaptation based on it forgets. Moreover, Hyde was not a hulking giant. He was actually smaller and younger-looking than Jekyll.
 * However, the last one is a misunderstanding over the statement that Hyde was growing taller and stronger, representing Jekyll's slide on the evil side. Alan Moore correctly recognizes the fact in the League of Extraordinary Gentlemen, along with the possibility of the hulking monster as a further stage.
 * In-universe in Salamander. The rules for magic are very different from what most people think they are.
 * It's commonly believed that almost every fantasy stereotype originated with Tolkien. He was extremely influential on the fantasy genre as a whole, but his descriptions of most fantasy races differ significantly from the stereotypical aspects of the genre.
 * In addition, very little of Tolkien's racial stereotyping originated with Tolkien. His sources were somewhat older. Trope Codifier, perhaps, but not Ur Example.
 * And while we're on the subject - The Lord of the Rings isn't Frodo Baggins, nor his uncle Bilbo. It refers exclusively to Sauron. There is only one Lord of the Rings, and he doesn't share his title.
 * Many people are still under the impression that Lewis Carroll was either on drugs or a child molester. The former comes from the time and space displacement that Alice undergoes during Alice in Wonderland (as well as the general nuttiness). In fact, Carrol suffered a condition now known as, appropriately, Alice in Wonderland Syndrome, which made him feel like he was growing or shrinking at random times. The general nuttiness comes from the fact that Alice in Wonderland was actually parodying just about everything Carroll could think of.
 * The child molester thing comes from a drastic misunderstanding of the fact that Carrol had a hobby of, er, taking photos of naked children. Victorian parents liked to collect nude photos of their children, and often sent them out with Christmas cards.
 * Contrary to popular belief, Carroll never actually referred to the Hatter as the Mad Hatter, only the Hatter. And the Queen of Hearts and Red Queen are not the same person.
 * While Carrie is telekinetic, her pyrokinesis is actually common knowledge. She never created fire using only her mind; she turned on the sprinklers in her school gym and ripped the cables of the rock band's instruments apart as well as the wiring in the gym itself. The current produced sparks which hit the mural behind the stage. The mural caught fire, which spread throughout the school until it hit the oil tanks and caused them to explode.
 * It's likely that Carrie is being confused here with the little girl from Firestarter, whose pyrokinesis is her main psychic power. Both books were by the same author and had young psychic girls blamelessly victimized by others as primary characters.
 * Eragon isn't the name of the dragon on the cover. It's the name of the farmboy who find the dragon egg.
 * Everyone knows that H.P. Lovecraft's stories are all about people meeting an ancient Eldritch Abomination (often the centerpiece Cthulhu), getting killed or turned insane by the end. Except that's not how the stories actually go.
 * Few of Lovecraft's stories feature an abomination itself—Cthulhu itself is only in the eponymous story, and mentioned fairly little beyond that. Yog-Sothoth is the most prevalent Old One in the mythos, which is why Lovecraft fittingly called his mythos "Yog-Sothothery".
 * The stories instead often depict smaller races who worship these Old Ones. Thematically, it focuses on humanity's lack of importance on a grander scale, rarely dealing with the actual end of the world.
 * Few protagonists of his tales go insane, and even fewer die. Most of them live, cursed to know about things they wish they didn't.
 * Nowhere in the original Dracula novel does it say that the titular character is weak against sunlight.
 * A lot of people think that in The Hitchhiker's Guide to the Galaxy series, 42 is "the meaning of life". Actually, it's specifically referred to as the Answer to the Ultimate Question of Life, the Universe, and Everything. The reason nobody can understand why 42 is the answer is because they don't actually know what the question is.
 * Books are not banned per se in Literature/Fahrenheit451. They're very rare, since nearly all books have been banned a la the Qin dynasty, and most "useful" books have been put on foresight's best approximation of digital media, but there exist books that are legal to own; there's even a scene where Montag tries to dramatically reveal that he's preserved a banned book, and everyone present thinks it's a "fireman"'s manual.
 * Remember the famous novel Alice in Wonderland by Lewis Carroll? She fell down a rabbit hole, talked to a doorknob and some sentient flowers in the garden, met Tweedledum and Tweedledee....wait, you mean she didn't? Well yes, of course she fell down the rabbit hole, but the talking doorknob was from the Disney animated film; while the talking flowers and Tweedledum and Tweedledee were both from "Alice Through the Looking-Glass". And common knowledge even gets the title wrong - it was "Alice's Adventures in Wonderland". Not to mention that common knowledge also screws up the sequel's title, as it is correctly ''Through the Looking Glass, and What Alice Found There".

Live Action TV

 * The Land of the Lost is not Earth in the distant past.
 * Common Knowledge from Star Trek:
 * The only thing everyone knows about Vulcans from Star Trek (apart from the pointy ears) is that they have no emotions. They in fact have very strong emotions--often described as more powerful than that of humans, to the point that, when combined with their strength, it led to anarchy that nearly destroyed them. This is why their culture now encourages all Vulcans to suppress emotion and act on logic. Their stoic nature is cultural, not genetic.
 * As mentioned above, Beam Me Up, Scotty is a subtrope of Common Knowledge -- with Star Trek providing the Trope Namer, since that line was never uttered in the original Star Trek series - the phrase the preceded beam-ups was usually something like "three to beam up". (If you wanna nitpick, we did get one "Scotty, beam me up" from one of the movies, where it was just the main seven or so characters on a Klingon ship). The main thing, however, is that, chief engineer Montgomery Scott was not the guy who usually did the beaming-up of people. That was a guy named Mr. Kyle that no one remembers.
 * Not every Gilligan's Island episode involved the castaways trying to escape the island, only about a third of them. Many episodes dealt with them trying to avoid being killed by tropical storms or some other threat, while a surprisingly large number were about things like having a costume party or a beauty pageant.
 * Also, everyone knows that all potential rescues/escapes failed because of Gilligan's screw-ups, and the castaways should've just eaten Gilligan, right? Actually, in the 37 episodes that involve some chance of getting off the island, Gilligan is only legitimately "at fault" for the failure 17 times. Screwing up 17 rescues probably would make you unpopular, granted, but there were also a large number of episodes where Gilligan saves the castaways from disaster, or headhunters, or some other deadly peril. There are also several instances where the escape plan was fatally flawed, but the flaw wasn't noticed until Gilligan had "screwed it up", inadvertently saving their lives.
 * There's also the common joke "How come the Professor could build a nuclear reactor out of coconuts, but he couldn't fix the hole in the boat?" In the first place, the Professor never built a nuclear reactor, and in the second place, the boat was completely destroyed in episode 8.
 * In 588 episodes of Lassie, Timmy never actually fell down a well.
 * Jokes about Lost often ask why "the fat guy," Hurley, never loses any weight on the island despite having a meager food supply. In actuality, the survivors of the plane crash had a variety of food to choose from, including boar and fish, and a research station full of consumer food was discovered in season 2. A Loose Change parody documentary on the fourth season DVD makes fun of this idea by asking how Hurley and the others retained their weight despite allegedly being stranded on a deserted island with little food.
 * Also, the show takes place over a much shorter time than it was aired. Seasons 1-4 took place over 108 days (this is specifically mentioned as )
 * At least one episode shows that Hurley has a horrible food problem; he's eating junk food from the mysterious sources (they got an airdrop once!) left and right.
 * And before the group found the junk food, Hurley specifically (and indignantly) tells Charlie that he has, in fact, shed quite a few pounds while on the island - it's just harder to notice such changes when they're such a small proportion of his total body weight than it would be if he were thinner.
 * The panel show QI has debunking things considered Common Knowledge, then explaining the facts, as its central concept.
 * In the show Doctor Who the main character's name is not, in fact, Doctor Who. It's just 'the Doctor'. Admittedly, this is partly the show's own fault for using 'Dr. Who' or 'Doctor Who' as the character's name in the credits over 19 seasons, but it can be rather irritating to fans when people don't seem to know who they're talking about until you add the extra word. Also, the TARDIS has the shape of a Police Box, not a Phone Booth (though it does have a non-working phone on the outside, and the Ninth and Eleventh Doctors have been shown operating a working phone attached to the TARDIS console).
 * On Starsky and Hutch, the heroes' chief informant Huggy Bear had a lot of different jobs over the course of the show, but pimp was not one of them.

Music

 * Despite it being disproven for years, there are still people who are convinced that "Puff The Magic Dragon" is nothing but a long, badly-hidden drug reference.
 * According to Word of God, "Purple Haze" is a love song where Jimi Hendrix describes a dream he had where he was walking under the ocean.
 * And similarly, "Lucy in the Sky with Diamonds" is what John Lennon's young son titled his drawing, not a thinly veiled LSD reference.
 * "99 Luftballons" means "99 Balloons" (there's no direct English translation, but the "luft" part specifies they're toy ones children carry, as opposed to a hot air balloon); indeed, not one line of the German lyrics mentions the balloons' colors. Nena added the word "red" to the English lyrics so it would scan a bit better.
 * Ragtime music is sometimes associated with The Great Depression era, but its popularity actually mostly died around around World War I and by the '30s was as far from its heyday of mainstream popularity as Disco music was in The Nineties or Grunge is today. The misconception was largely fueled by the 1973 film The Sting, which featured a prominent ragtime soundtrack and was set in 1936.
 * Everyone knows that "Louie, Louie" was the filthiest, most obscene song you could commonly hear on the radio (before such controversy caused people to lash out against it). In fact, it's just a completely unintelligible telling of a simple story. The creators themselves have gotten into screaming matches with fans over what the lyrics "allegedly" are.
 * Many people still think that Warrant hated the song "Cherry Pie." This isn't actually true. It is true it was something they wrote quickly, but they don't hate it and have said as much. The songwriter just flipped out during an interview because his life was falling apart at the time during the question about that particular song.

Mythology and Religion

 * King Arthur pulled Excalibur, the sword in the stone, thus proving he was king of England. Except that in most versions of the legend the sword he pulled out was an entirely separate (usually unnamed) sword. Excalibur was given him by the Lady of the Lake after the Sword in the Stone broke.
 * Also, it seems to be Common Knowledge on this wiki that the Sword in the Stone is called Caliburn. It's not. Caliburn is simply an older word for 'Excalibur', and whilst it has been used in some of the original tellings of the legend to mean the Sword in the Stone, that's only in versions of the legend where Excalibur and the Sword in the Stone are the same sword (or, at least, have the same name). The notion of Caliburn and Excalibur being different swords came much later.
 * Similarly, in the earlier texts, the Holy Grail was not a cup, nor was it even referred to as holy. It its first appearance, Perceval, le Conte du Graal, which translates into The Story of the Grail, it appeared as a dish.
 * It's also worth observing that the King Arthur stories are older than the Holy Grail's inclusion. There are a lot of people who think the King Arthur tales are always about Holy Grails and Lancelot/Guinevere betrayals and don't realise versions exist without them.
 * King Arthur is more properly a legendary king of Britain, not England; in early traditions Arthur is said to have fought the Anglo-Saxons who gave the name England ("land of the Angles") to Britain.
 * For Christianity; everybody "knows" that Satan and the demons rule over hell to torment the damned. Except that The Bible plainly says that Satan and his demons will be punished right along with the damned. Hell is Satan's prison, not his kingdom. (His kingdom is actually earth.) Also, Satan, along with every other demon, was once a glorious angel, and they rebelled against God. In Christian belief, nothing originated as evil.
 * The word "ha-satan" in Hebrew literally means "the opposer". This is made fairly explicit in the book of Job, where Satan is a angelic minion whose purpose is to test humans to see if they will continue to obey the laws of god when forced to suffer.
 * Continuing the Hell theme: fire, brimstone and eternal torment are often described as "Old Testament". The Old Testament does not mention Hell at all. The entire concept is a Christian innovation (maybe inspired by the Zoroastrians, but just as likely as a misconception of the passages in Revelation (no "s" at the end, btw) that describes God throwing death, Hell, etc. into a lake of fire and brimstone, after Judgment Day).
 * Also, the Immaculate Conception is not the conception of Jesus by the Virgin Mary, but the idea that Mary herself was born free from original sin. Unlike the virgin birth, which is universal to all denominations of Christianity, the Immaculate Conception is a specifically Catholic dogma that is rejected by a majority of Protestant, Orthodox, and Anglican churches.
 * Anything covered by Word of Dante qualifies. Paradise Lost especially has greatly changed how people view the basic setup, despite not being intended or recognized as canon.
 * Mary Magdelene was never identified as a whore. She is mentioned for the first time in a passage following one about a whore. The two women were officially combined hundreds of years later in order to cut down on the number of characters. Mary came to Jesus with "demons in her head," most likely referring to her having some sort of mental illness that he cured.
 * In addition, we never see Mary Magdalene anoint Jesus with perfume or wash his feet in the Gospels. The unnamed "woman who was a sinner" mentioned above did that, and much later, just before his death, a different Mary anointed him with perfume again—but that was Mary of Bethany, the sister of Martha and Lazarus.
 * On the subject of biblical whores, the woman to be stoned in John was certainly not one. She was an adulteress, which under Mosaic law, meant she must have been married; a single woman sleeping with a married man was not considered adultery. Prostitution was not only legal, but almost expected if a woman had slept with (or even been raped by) a man who refused to marry her.
 * At this point nearly everyone knows that the wavy, brown hair seen on the Semitic Jesus is just artistic license, but the idea that he had long hair at all is unlikely, since Paul later refers to long hair on men as "a disgrace," an odd thing to say about your Saviour. It's likely that what constituted "long" hair was different in those days, but the way Christ is usually depicted, with hair well down his back, certainly would have counted. Likewise, the ethereal beauty he's usually depicted with is explicitly contradicted by Isaiah, if it's to be believed that Isaiah's prophecy refers to him. And given that Jesus grew up as a hard-working carpenter, it's unlikely that "ethereal" would in any way apply to him.
 * Of the four horsemen of the first four seals, only Death's role is made explicit. War and Famine are identified by the first carrying a large sword and going off to make war and sow strife, and the second holding a scale while a voice behind him cites hugely inflated grain prices and warns against touching pricier goods. Fair enough. Pestilence is thornier, and indeed, to the Catholic and Orthodox Churches the first horseman is "Conquest," since he identifies himself as a conqueror; other traditions have him as Christ himself or the Antichrist. Since conquest and war are so closely related, however, a minority of theologians came to the conclusion that this is the metaphorical conqueror of "Pestilence," and this idea somehow stuck.
 * Everyone knows that the Mark of Cain was a curse placed upon Cain by God. Except that, if you actually read the story, it isn't. God cursed Cain, then when Cain complained that on top of that anyone he met would kill him, God blessed him with a mark of protection such that any who harmed him would suffer vengeance sevenfold. This countered Cain's objection and ensured that he would only suffer the intended curse.
 * Many people believe Sodom and Gomorrah were destroyed because of homosexuality, but the book of Ezekiel (16:49 if you're interested) confirms that they were destroyed for greed and selfishness.
 * Greed, selfishness, and barbarism; in the passage that most people cite as the source of the homosexuality myth, the mob attempts to get Lot to release the angels visiting him to them so they could "know them". When Lot refuses and offers them his virgin daughters, instead, the mob refuses, threatens Lot with violence, and gets struck blind by the angels when they attempted to make good on their threats. Sadly, this hostility in the mob gets condensed down in most peoples' minds as "they were gay", and are often combined with the Law of Moses stating "man should not lay down with man" as "proof" that the bible denounces homosexuality.
 * That would have made sense if Lot didn't offer himself and got rejected too.
 * The angel Gabriel was not an archangel. He was a seraph. By definition there can only be one archangel, and the Bible only mentions one, and that is Michael. Michael, Gabriel and Rafael were all seraphs, the highest order of angels, but Michael alone was the archangel - the highest among angels.
 * Actually, it's more confusing that that. Some of the listings of angels differentiate archangels and Archangels, with the lower case being a lower, serving set of angels counter to our concept of "arch" indicating highest and the capital being the order of angels that sit closest to God. However, the Bible itself rarely makes any comment more definite than "thousands of angels" and most of the listings are made outside the Bible and have grown to include the various deities of minor villages which were anglicized in order to attract more worshipers to the church by convincing people that their gods worked for the true "God".
 * Christians do not become angels when they go to heaven. They just go to heaven. Angels are an entirely separate order created by God, and none of them were ever human.
 * Lucifer is Satan. There is heavy evidence that the Lucifer mentioned in the Bible is actually a particular king who was also known as the "Bringer of Light" because he literally brought light to the nighttime streets of his city, but who fell into ignoring his responsibilities later in light. There is no indication that there is an angel named Lucifer in the Bible.
 * Noah did not just bring two of every animal aboard the ark. He brought two of every unclean animal, seven of every clean animal, and seven of every bird. After all, birds live in flocks, and if you're going to eat some lamb, you'd probably want to take more than two lambs, right?
 * The Magi did not come to visit Christ on the day of his birth at the stable. By then, some time had passed and Jesus's family is noted to be living in a house. Indeed, the story of Herod and the Magi is found in Matthew, whereas the story of the census and the inn is in Luke - nothing in Matthew suggests that Mary and Joseph did not live in Bethlehem before fleeing to Egypt (the two birth narratives, while not necessarily irreconcilable, have very few details in common).
 * Job's wife did not die. His children all died, and his slaves, but his wife is actually a minor character in her own right (Job's misfortunes all come in the opening chapters).
 * Many/Most of the examples listed under Sadly Mythtaken.
 * Oedipus killed his father and slept with his mother. While that is factually true, most people assume that he knew about this fact, which he didn't. He had no clue that the man he killed was his father nor that the woman he had sex with was his mother. His parents in fact had their son's fate foretold to them, so they left him for dead. He was then adopted and, once he reached adulthood, heard a similar prophecy and went to drastic lengths to avoid doing such horrible things to people he thought were his parents. He then got into a fight with a stranger and killed him, not knowing that it was the king of Thebes. He later married the recently widowed queen of Thebes as a reward for ridding the city of the Sphinx on his way to the city; some versions of the story have the queen wearing a necklace that kept her youthful, thus making it even less likely that Oedipus would think she was his mother. It was many years again before anyone learned the truth. The Oedipus Complex which is named after him doesn't help this misconception.
 * There is no singular "the" Buddha. "Buddha" is a state of being that very few can achieve, Siddhartha Gautama being among them, the only one within human history as we know it. This is why some Buddha statues depict an obese Chinese man rather than a thin Indian one; this is a tenth-century monk whose future incarnation is believed to be the Maitreya Buddha, who will end our age.
 * Greek mythology does not state that Atlas was forced to hold the Earth on his shoulders. He was actually forced to hold the heavens on his shoulders.
 * Loki was a full-blooded jotun, not a half-jotun. (This notion probably got started by The Mighty Thor.)

Professional Wrestling

 * At Over The Edge 1999, no one watching on PPV saw Owen Hart fall to his death. He was being lowered during a pre-taped interview segment, which didn't cut away until he had hit bottom.
 * There are a lot of things that are Common Knowledge in the IWC which can easily be disproven by looking at things like ratings and sales would easily disprove. Like that the WCW and ECW Invasion in 2001 was a ratings disaster despite the ratings showing that it actually viewership remained steady and even went up a little during the angle until near the end when Real Life events drew people away from it.
 * Several people claim that Shawn Michaels gave up the WWF title because he lost his smile however they are confusing 2 vary different promos that happened months apart. At Survivor Series 96 Shawn lost the belt to his one time friend Sycho Sid after Sid attacked Michaels’ mentor and manager Jose Lothario, a week later HBK gave an interview where the always upbeat former champion said the event caused to be afraid for his mentors safety and it hurt him more than losing the belt, it made him lose his smile. Two months later Michaels regained the belt at the Royal Rumble but suffered a saver knee injury and needed surgery so he would be out of action for at least six month and maybe permanently. He gave up the title on Thursday Raw Thursday in a Tear Jerker speech where he made a brief reference to the earlier promo, somehow the two became intertwined in peoples mind and they decided that “lost my smile”, was Shawn’s reason for giving up the belt and came out of left field despite the two being two very different things
 * it also became Common Knowledge that he only claimed to have lost his smile so he would not have to lose the title to Bret Hart at Wrestlemania and did not even need surgery. This is strange for a couple of reasons, first Michaels surgery was covered on tv and they even showed footage of him getting the operation done and he walked with a cane on tv for several weeks while he recovered and returned to his old job as a commentator. Secondly Hart was at the time the most booed face in the company after his 7 month vacation and feud with Stone Cold Steve Austin it is unlikely that they would give him the belt at the biggest event of the year, also they did give him a brief rain by winning the Final Four and losing it the next night to Sycho Sid, they could have easily had Hart as champion at Wrestlmania without Michaels he just was not over enough to justify it.

Sports

 * Contrary to popular beliefs, Oakland Raiders Owner/GM Al Davis was neither a member of "The Foolish Club", the eight original team owners of the American Football League (AFL) nor was he the Raiders original head coach. Davis did not assume control of the Raiders until 1967. He was an assisant coach under Hall of Fame coach Sid Gillman for the Los Angeles/San Diego Chargers for the AFL's first three seasons (1960-1962), and head coach of the Raiders (Hired by actual original Raiders owner F. Wayne Valley) from 1963 to 1965, before handing things over to John Rauch (Which is yet another bit of "common knowledge": John Madden was not Davis' immediate successor.)
 * The so-called "Tom Brady Rule" (which prohibited a defensive player from hitting quarterbacks below the knee) was wrongly attributed to Tom Brady after his season-ending knee injury during the 2008 NFL season. It's unofficially called the "Carson Palmer Rule" (which Brady calls his knee injury in a interview with WEEI radio), which was passed back at the start of the 2006 season after Cincinnati Bengals QB Carson Palmer suffered the same injury during the 2005 playoffs against the Pittsburgh Steelers. The actual "Brady Rule" (or amendment) updated the existing "Palmer Rule" by stating that a defender who's already on the ground can't hit the QB below the knees.
 * The general consensus on the 2007 Spygate scandal is that the New England Patriots are cheaters. In actuality, the Patriots were found guilty of recording the New York Jets' defensive signals from an illegal location (i.e., the sidelines). Also, Super Bowl-winning coaches Jimmy Johnson, Bill Cowher, Dick Vermeil, and Mike Shanahan admitted to doing the same thing.

Theatre

 * "Pirate" is never rhymed with "pilot" in The Pirates of Penzance, even in the song about Ruth's confusion between the two words.
 * While the famous line from Romeo and Juliet: "O Romeo, Romeo! wherefore art thou Romeo?" is usually quoted right, more or less, most people are unaware of the true meaning, often believing that Juliet is asking "Where are you Romeo?" Note that "wherefore" does not mean "where", it means "why". Compare "therefore". In other words Juliet is asking why Romeo must be who he is, a member of the family with which her own family has a long-standing feud.
 * Also, "star-crossed lovers" is not a synonym for "happily ever after". It means they have crossed or defied their fates, the stars. They die.
 * Similarly, Hamlets "The lady doth protest too much, methinks" doesn't mean she complains in a suspiciously over-the-top manner. It means that she promises more than she can reasonably deliver.

Video Games

 * Final Fantasy II for the SNES was not based on Final Fantasy IV Easytype; it's the other way around. Although Final Fantasy IV Easytype was released first, it was a port back of the changes made in Final Fantasy II to the Japanese version, and also has a few key differences from Final Fantasy II; the most notable being that it has an entirely new version of Zeromus, while Final Fantasy II just had a downgraded version of the original Final Fantasy IV Zeromus.
 * Ports cost almost nothing to make, because it's just moving data from one system to another, which is why any port to a more powerful system (or less powerful) is shovelware. Except none of that is true. Even if the systems are nearly identical (like Game Cube games to the Wii) they are not actually identical, and you need plenty of testing to catch any unforeseen incompatibilities. If the systems are different, and/or less powerful than what the game is being ported from, you have to rewrite the whole damn thing. That often means the only money saved is on design (since the game is already made). People bashing ports for being cheap clearly Did Not Do the Research. Developers acting like the myth is true is a major cause of Porting Disaster.
 * The Legend of Zelda series has no continuity or plotline, and is simply the same game done over and over with different graphics. In reality, Zelda has a notoriously complicated timeline, only fully revealed to the public (and even then, only in Japanese) in the 2011 book Hyrule Historia, which splits into three separate alternate timelines at the end of Ocarina of Time (fan theories had previously assumed two alternate timelines at this point). More recent Zelda games, like Twilight Princess and Spirit Tracks have included more and more references to earlier games, indicating Nintendo is aware of this misplaced criticism.
 * On that same note, "Link" is not a singular character, nor is Zelda. There have been many Links (who may or may not be related) and many Zeldas (who are all part of the same royal line ). Only Ganon(dorf) remains the same person from game to game. You will be Gannon Banned for claiming Link or Zelda is the same person in every game.
 * A lot of people seem to be under the impression that the multiplayer modes of Four Swords and Four Swords Adventures require four players (probably because of the title). In actuality they can be played with two or three people as well. So you don't have to worry about having to buy four GBA systems and cables if you only really want to play in a two or three player game. And Adventures can even be played single-player; so can the D Si port of Four Swords.
 * In the same vein as the Zelda example, there is, in fact, a Mario canon, which is generally agreed upon to include the main console games and certain handheld games (usually ones that introduced new characters).
 * Continuing the Nintendo examples, Pokémon does have a canon plotline within the games. Pokémon FireRed and LeafGreen take place during the same time period as Pokémon Ruby and Sapphire; Pokémon HeartGold and SoulSilver take place around the same time period as Pokémon Diamond and Pearl (three years later). Gold and Silver are perhaps most notable for including the entire Kanto region from Red and Blue with references to the earlier games galore, while Ruby and Sapphire are more subtle with their references to the fact that Gold and Silver haven't happened yet. Abundant references to Johto in Diamond and Pearl led fans to the (accurate) assumption that Gold and Silver would be remade. Pokémon Black and White take place sometime after all other games; references the events of Platinum and a Team Plasma Grunt references the failings of Team Rocket and Team Galactic.
 * While Pokemon certainly has a canon plotline, Ruby, Sapphire and Emerald have yet to be pinned to a specific time in it, other than likely prior to HGSS.
 * Another Pokémon example: not a single player character in the series is 10 years old. Not one. At least, it hasn't been specified. The only player character to have their age confirmed is Red, who is said to be eleven years old as of Generation I (and III). The reason the whole "ten years old" thing has been engrained in the public consciousness is because of the popularity of the anime, who's main character is 10. Eternally.
 * Similar to that, nowhere in the games is it said that you must be ten to be a trainer or that all trainers start at age ten. In fact in the games you see trainers who are way younger than ten - think 4 or 5 years old at youngest and in Pokémon Black and White you begin your journey in your mid to late teenage years. Most trainers in the 4 - 11 year old range don't wander that far from towns or areas with a lot of people, it's the older teens and up who you see on journeys (like Ace Trainers).
 * All trainers get Pokedexes.. Except they don't. You're a special case, along with some other select trainers.
 * It should be noted that many of the misconceptions about the game are true for the anime, and vice versa. To say nothing of the various other adaptations and derivative works, which may well have completely unrelated canon. So the Common Knowledge in many cases is just a form of "All variations of Pokémon have the same rules and background".
 * Yet another Nintendo-related example: the console known as the Wii was never supposed to be called the "Revolution." This was a working production name, just like the "Dolphin" (Game Cube) or "Nitro" (DS). However, due to Nintendo revealing a great deal of information about the console before it had a name, media sources were forced to use the name Revolution over and over again until the public loved it so much that when the actual, controversial name was revealed, there was a backlash.
 * And now another Nintendo example: Nintendo's consoles are always the weakest in each generation. Actually, the SNES technically surpassed the Sega Genesis in almost every way, it was just that the Genesis marketed its meaningless "Blast Processing" far more than Nintendo marketed any of its console's features. Next, the N64 had many advantages over the PlayStation and Sega Saturn: more RAM, pushing more polygons in real time, and some other graphical features, however, it wasn't as developer friendly as its rivals (and its cartridge-based games had much lower storage capacity than the Playstation and Saturn's CD-ROMs, which proved to be a significant handicap in an era when developers increasingly wanted to include FMV cutscenes in their games), so third parties generally went for the Playstation. The Game Cube was actually more powerful than the PlayStation 2 and only slightly less than the Xbox. According to some, it was even easier to program for than the PlayStation 2, but since the PlayStation 2 already had an established base, and the Xbox was even easier to program for, developers ignored this system, too. The only time that this is correct is with the Wii, whose architecture was built off of the Gamecube's and focused more on innovation than power. The misconception could be due to Nintendo's "Lateral thinking of withered technology" policy on building hardware, but Gunpei Yokoi, creator of the policy, didn't think of it as such.
 * The only place there's been a real element of truth to this conception has been with handheld game consoles, given that it took surprisingly long for the Game Boy to be given such basic features as a backlight to play in the dark and a color screen, despite competitors like the Atari Lynx and Sega Game Gear appearing within a year of its release that did have those features. However, the more powerful competitors to Nintendo's handhelds tended to have crippling flaws, like much higher prices and horribly short battery life. Thus, the Game Boy line of handhelds utterly dominated the market until Nintendo voluntarily retired the name in favor of the new Nintendo DS...which followed in the Game Boy's footsteps by continuing to own the handheld market.
 * Third party developers choose consoles based on the technical specifications when comparing consoles from the same generation is largely a myth. There are a few developers that choose platform based on specification, but they are the exception not the rule. The two most important criteria are how easy it is to work with the company and regional sales.
 * The main misconception is that Nintendo consoles have had the worst third party support since the 16 bit generation because their consoles were inferior. This is incorrect. Nintendo is hands down the worst company for developer's to work with. Nintendo has always been highly restrictive with content on third party games, refused to make compromises over business deals, and used to sue almost any developer that worked with them that remotely touched on anything Nintendo didn't like with their games.
 * The Xbox 360 vs PlayStation 3 war is more in the heads of consumers than anything else. Total sales between the two consoles are fairly similar, but this is somewhat misleading. In Japan, Play Station 3 sales far exceed Xbox 360. In North America, Xbox 360 sales far exceed PlayStation 3. Europe is fairly evenly divided between the two. Most developers choose the console to develop for based on whether they think Japanese or North American sales will be higher, not based on specs.
 * Who killed Aerith in Final Fantasy VII? Sephiroth, right? Not exactly. It was Jenova, acting as his avatar. Sephiroth actually spends most of the game hibernating in the Whirlwind Maze. Of course, because that part of Jenova changed its form to appear as Sephiroth, and acted as a puppet of his will, you could say "it was Sephiroth" and technically, you'd be right. The "real" Sephiroth is only encountered twice in the entire game: once in the Whirlwind Maze and once as the final boss.
 * Similarly, it was the body of Jenova, shape-shifted to look like Sephiroth, which broke out of Shinra HQ and which the party was pursuing throughout Disc 1.
 * The various "clones" encountered in the game are actually the former residents of Nibelheim, injected with Sephiroth's cells and exposed to Mako energy in an attempt to create duplicates of the fallen super-soldier (or maybe just to give him some pawns to manipulate).
 * Cloud's androgynous Bishounen look wasn't introduced until Advent Children, yet he's often spoken of as if said look was always his design.
 * Speaking of Cloud, his characterization as "emo" is largely due to Fan Dumb and the Complete Collection. In the game proper, Cloud was a cocky punk who grew into a confident leader at the game's end, and that's after realizing that said "cocky punk" attitude was more of Zack's behavior that Cloud had imprinted onto his own memories. And while Cloud does have some moments of angst in the game (namely about how Sephiroth burned down Cloud's hometown and killed his parents, something Cloud would rightly want revenge for), the worst of it is after a massive Mind Rape that leaves him stuck in a wheelchair, babbling incoherently. And even then, after Tifa helps him snap out of it with a Battle in the Center of the Mind, Cloud stops angsting about everything and focuses on defeating Sephiroth to save the world. Advent Children has Cloud suffering from the effects of Geostigma, and while Cloud is pretty whiny here, it's heavily implied that the disease is messing with his mind. Notably, after the Geostigma is cured at the end of the movie, Cloud is seen smiling and happy.
 * The Blazing Star "YOU FAIL IT! Your skill is not enough. See you next time. Bye bye!" screen. It appears when you time out a boss, yes, but most people who have not actually seen the screen first-hand think it's part of a Nonstandard Game Over. In actuality, timing out a boss will simply take you to the next stage; the screen is just the game's way of telling you that you lose your end-of-stage bonuses for taking too long.
 * Nintendo's fanbase frequently cries that it needs new franchises, instead of just Super Mario Bros (1981, 1983, or 1985, depending on interpretation), The Legend of Zelda (1986), and Metroid (1986). Strangely enough, Pokémon is often included in the list, despite it starting in 1996. Even assuming Pokémon was the last "new" franchise, we still have Custom Robo (1999), Pikmin and Golden Sun(2001), The Legendary Starfy(2002), Brain Age, Drill Dozer and Battalion Wars (2005), Wii Sports and Rhythm Heaven(2006) and Hotel Dusk: Room 215(2007). And that's not even including all the Mario spinoffs that have little-to-nothing to do with platforming or kart racing.
 * Sony/Microsoft/Nintendo paid "X" to make an exclusive to boost console sales is a very common, very erroneous statement in virtually every situation it is used.
 * The main source of revenue for console companies is licensing fees. This means developers and publishers pay them for the right to develop a game in the first place. They might offer incentives for companies, such as lower licensing fees or preferential treatment, but actually paying them is a different thing entirely.
 * All three companies are also publishers. If they are giving a company money, it is virtually always as a publisher (or at least an investor). They are directly profiting off the game itself regardless of what console it is developed on. While all the companies do consistently only invest in console exclusive games, it is not unheard of for there to be multiplatform releases. Sony used to own a large, but not controlling share of Squaresoft, yet, were unable to prevent multiplatform releases on several major games. Squaresoft was more Sony exclusive before Sony invested in them then after. Publishing and consoles are different divisions with different objectives and goals.
 * There is a huge overhead cost for any console development. Most console exclusive games come from developers being unable or unwilling to pay those costs and hire experienced programmers for each console type.
 * Some genres of games just do poorly on specific consoles, which lead to companies designing for a specific console. This can be seen by looking at the sales numbers of the large titles that do multiplatform releases. JRP Gs, for example, typically do very poorly on the Xbox 360 in comparison to the PlayStation 3 version. Final Fantasy XIII did not sell proportionately between the two consoles based on total sales. The American Play Station 3 version even significantly outsold the Xbox 360 version, despite there being nearly twice as many Xbox 360 owners as Play Station 3 owners in that region. Western Role-Playing Games, such as Dragon Age: Origins, show the reverse trend.
 * One of the most common complaints about Downloadable Content is that any DLC, especially if it's available at launch, is clearly content the developers removed from the game to make money. Problem is, even Day-1 DLC is usually planned into the development process of the game, and may be announced months ahead of time, yet irate gamers will still insist it was yanked out at the last minute. Of course, most of these complaints are based on sour graping rather than any rationality in the first place. Note that even DLC that is released weeks after the game's launch has been accused of being a cash grab, and the complainants never seem to explain what sort of gap would make it "obvious" the DLC is original content.
 * The most vehement griping comes when the DLC is to unlock content that's already on the game disc, though. And many fans consider the very concept of DLC to be a cash-grab and a curse on gaming.
 * Of course, people are notoriously loose in defining what counts as "already on the game disc." For instance, the Prothean party member for Mass Effect 3 is frequently cited, because they ended up including the base character on the disc to smooth integration of the DLC with the core game—the fact that said download is over 600 megabytes is a fair indication that not everything from the DLC is on the disc.
 * Scorpion and Sub-Zero. One of the most bitter rivalries in gaming, right? Well, not really. Scorpion got his revenge over Bi-Han, the original Sub-Zero at the end of the first game. In Mortal Kombat 2, we meet Kuai Liang, the new Sub-Zero (and Bi-Han's younger brother). Scorpion actually becomes the protector of this new Sub-Zero, to atone for killing his brother. Aside from briefly attacking him during the fourth game (due to being Brainwashed and Crazy), Scorpion remains watching over for the rest of the series (at least until the reboot, which goes in a different direction.).
 * Sonic the Hedgehog is often thought of as being aquaphobic. While this is canon in some adaptations, it isn't canon in the games. He simply can't swim and has the same fear of drowning that everyone else has, especially people who can't swim.
 * Also everyone knows that his love of chili-dogs became game canon in the Sonic Storybook Series.. Except it was made canon in Sonic Advance 3's Japanese manual. There's also some common misinformation about where his love for hot-dogs came from - the earliest known reference was in an early Sonic the Comic issue (though it was regular veggie dogs instead of chili dogs).
 * It's common knowledge that Poison and Roxy in Final Fight were made into Transsexualism women due to Nintendo of America's issues with hitting women at the period... Except Poison was transgender in Japan since the get-go. She's always been called a "new-half".
 * It's not entirely Common Knowledge. Poison and Roxy originally were female and were changed to Transexual characters because Nintendo believed American gamers would have a problem hitting women. The Common Knowledge aspect is when the change occurred. They were changed to transvestite before their first appearance, but the overall reason for them not being female is correct.
 * Mario does not open blocks by hitting them with his head. If you look closely, he actually punches them.

Webcomics

 * Something*Positive's creator R.K. Milholland gets a lot of complaints grounded in this trope from readers; the most common objection is "Your comic didn't used to be mean," despite the fact that the main character sent a coat hanger to an ex-girlfriend as a baby shower present in the first strip.
 * CRFH's trio of male protagonists all acquired a mutant ability: Mike's arm was replaced with a superstrong tentacle, Dave got laser vision, and Roger got an eye in his hand, not his were-coyote nature, even though that's often mistakenly cited: he had that already. The confusion arises because this is what Roger uses when they have to fight, alongside the others' abilities, and because the eye in the hand hasn't been mentioned in a long time.
 * Penny and Aggie are not Canadian. In early strips, T and Gisèle put them in a purposefully ambiguous location on the Eastern Seaboard, and due to a previous collaboration by them set in Canada, many assumed this one to be set there as well, some ex-readers or (very) casual readers still so assuming. However, as strip became more plot-driven, T was forced to choose a side of the border, and the setting is now unarguably American even to someone who's only read the comic proper.
 * For Homestuck a lot of the time, all non-fans really know is that the main characters/most popular characters are the grey-skinned alien trolls. Nope - the trolls don't arrive until act 4, and then not in person until act 5, and while they're not all minor characters they are definitely subordinate to the kids. Also, while they're certainly popular with the fandom, the fact that they show up so often in fanart is probably more to do with the fact that there are a hell of a lot of them, and that Andrew Hussie is very, very good at characterisation, so even the Those Two Guys equivalents have quite distinct personalities.
 * Casual fans or non-fans associated with the fandom also usually think the series has a lot of gay romance. In actuality, there are two gay characters, and a few bisexual characters, none of whom have their romances anywhere near seriously taken. The most common one, John/Karkat, was immediately sunk as a ship after it was introduced canonically, but to hear the fandom, it's pretty much all the series is about. In fact, the portrayal of the gay characters is not without Unfortunate Implications, since the bisexual characters are mostly But Not Too Bi and the same-sex relationships tend to be portrayed as creepy, hopeless, or Played for Laughs.

Western Animation

 * All Animation Is Disney. Only it's not...
 * Despite what anyone tells you X Men Evolution did not move the location of the Academy to California. It just took place in a...very California-like New York. Which admittedly is really odd because it's animated.
 * The same one from the live-action movies, apparently. Rogue states at one point that it never snows in upstate New York.
 * Steamboat Willie is often credited as the very first Mickey Mouse short. However, Mickey and Minnie appeared six months earlier in Plane Crazy, which was produced first, but Disney couldn't sell it. Steamboat Willie was the short that made a star out of Mickey because it was the first short to use sound properly, allowing him to stand out from other cartoons, which is why the short sold. On that note, it's not Pete's first appearance either; he was antagonizing Oswald and, before that, Alice.
 * On that note, Snow White and The Seven Dwarfs is not the first full length animated feature. It is the first to be released in America, the first from Disney, and the first to turn a profit and be successful, but other animated films were released in other countries before it.
 * "Girl's Night Out", the episode of the DCAU featuring Batgirl and Supergirl against Poison Ivy, Harley Quinn, and Livewire, is commonly thought to be a Superman: The Animated Series episode, but in reality, it's officially a Batman: The Animated Series episode, according to both the episode list on the official website and the fact that it was on the B: TAS Volume 4 DVD rather than Volume 3 of S: TAS (which included the last third of the series, including Supergirl's debut).
 * Transformers: Optimus Prime actually turned into a cab-over truck, not a regular truck. A cab-over is a special kind of truck which has a flat face and the cab sits above the front axle. A regular truck has the cab behind the axle giving the front an elongated look. The Movie features his alternate mode as a regular elongated truck because the animators found that, with their commitment to avoiding mass-shifting, a cab-over model resulted in an unimpressively-short Optimus; some subsequent adaptations, including Transformers Prime, followed its lead.
 * Prior to the live-action movies, several Optimus Prime toys were released in regular truck forms, most notably the Combat Hero Optimus Prime and Laser Optimus Prime from the Generation 2 line. Their only non-toy appearance was a brief appearance of the Combat Hero version at the end of the G2 comic.
 * Many people are under the misconception that the creators of South Park are anti-religious. After an episode about Muhammad was made and they recieved death threats, Bill Maher and Seth Macfarlane defended them for being against religion. They are NOT against religion, as the commentaries for episodes like "Red Hot Catholic Love" and "All About the Mormons" has them clearly state that if you're a genuinely good person, it doesn't matter what you believe.
 * This is explicitly stated in the two parter "Do the Handicapped go to Hell?" and "Probably". The episodes, although they portray fundamentalism and "fire and brimstone" preaching in a negative light, clearly Sister Ann, who argues that "if people are good, they can get into Heaven" is portrayed as the Only Sane Man and even Jesus comes in later and reiterates this message.
 * Krang from the 1987 Teenage Mutant Ninja Turtles was not a Utrom. It's true his appearance was inspired by the Utroms, but he is himself a disembodied brain from another dimension. The Utroms are brain like creatures from another planet.

Real Life

 * Just about everything people today know about King John of England is common knowledge, he was actually a very skilled diplomat and general and under him England was bigger then it had been under any king since the House of Danes ruled and would not be that big again until the house of Stewart. He was able to get most of Ireland to recognize him as lord, and also took significant land in Wales and Scotland which England continued to hold for centuries. He also did not inherit any French land, his brother King Richard had lost all of it to King Philip II of France by the time John became King. He was able to retake most of them and then lose them again a couple times (they were finally given up by his son Henry III). He also inherited the Duchy of Aquitaine after his mother died meaning that he actually had more French land then when he started. He was also able to re-establish England’s independence form the Holy Roman Empire which it had become a vassal state of under Richard. John also was considered to be to kind and friendly with the Jews which was one of the things his enemies used to rally against him. He also was not tricked or forced to sign the Magna Carta. It was a peace agreement between him and rebellious Lords that he did not want to fight with because he was preparing to invade France. However they then changed the treaty after it was signed to give them more power and authority then was agreed to and so King John had it null and voided by the Pope. The fact that no other king was named John was not a slight against him but an unfortunate coincidence as 3 crown princes were named John. He did not receive his Historical Villain Upgrade until about 500 years after he died when somebody decided to make him the antagonist of Robin Hood who had previously been fighting his grandson King Edward. About the only thing that people know about him that was true is he increased taxes on the nobles, which were a necessity as he needed a bigger army for the bigger kingdom and also had to pay a lot of people for his brother mistakes like getting captured and held for ransom by the Holy Roman Empire.
 * King Henry VIII of England also has a lot of "common knowledge" associated with him. First and foremost it is that he never had a son survive childhood which is false as he had just as many recognized sons as daughters: 2. The first was Henry Fitz Roy Duke of Richmond and Somerset, who was illegitimate and survived into his late teens. The other and more important one was King Edward, while he was also in his late teens when he died but he did something that would have an impact on England till this day which his father is given credit for. It is also common knowledge that he had all his wives beheaded because they could not provide him a male heir. While it is true that he divorced his first wife, Catherine of Aragon, for this reason, she was also unable to have a daughter as she was in her late 40’s and had stopped menstruating (the armed rebellions she supported against him probably also had something to do with it). As for the other wives two were beheaded for adultery, one died in childbirth, one was a political marriage designed to create an alliance which fell through and the final one survived him. He also was not the founder of the Anglican church or even converted to Protestantism, he just refused to recognize the current Popes because they were pretty much puppets of Holy Roman Emperor Charles V at the time. He considered himself catholic and even kept the title Defender of the Faith given to him by the church. Finally he was also fit active and handsome for most of his life. While it is true that in later years health problems limited his mobility and caused him to gain a lot of weight he was not like that for most of his life.
 * Columbus did not prove the world was round. There is no record of a mainstream, educated Christian believing the Earth to be flat, and many to the contrary. Some early civilizations believed it to be flat or rectangular, but in every culture informed by Pythagoras, this has been a fringe theory. Seafaring cultures had long known about the curious phenomenon of not seeing another ship's lower hull if they were far away enough. This is because of the curvature of the earth - and you can see it on land in the right places too.
 * The Chinese held onto the theory much longer, since unlike the Europeans, they didn't travel much by sea, nor have very much contact with those who did; maybe if Columbus had been right about the circumference of the Earth (which, against the science of the time, he conveniently thought was about one Pacific Ocean less - the real reason he couldn't get funding) and the sparsity of Western land, he'd have told them.
 * The real reason Columbus couldn't get funding is that he was in fact an Average Joe with fabulous idée fixe. He wasn't a traveler or sailor of any kind (a trader at several merchant ships is the closest thing) and had possessed literally zero knowledge about navigation. In modern terms, he can be easily recognized as a con man, with queen Isabella being a victim of the fraud.
 * He wasn't even the first European to discover the American continents. Nor did he even reach the actual continents until his third and fourth voyages. His now-celebrated first voyage in 1492 discovered only some islands.

""Finally, Giles Corey cried out "More weight!" and died.""
 * The concept of Drinking the Kool Aid, as its entry explains, did not originate with the Jonestown Cult suicide. This has led to some confusion about the incident itself, namely The victims drank poisoned Flavor Aid, not Kool-Aid;
 * Napoleon Bonaparte was supposedly short, and he has been ruthlessly parodied this way for centuries ever since. A 'Napoleon Complex' is someone who has an inferiority complex based on their short stature, and make up for it in some way (though not everyone has the gifts to conquer Europe to make up for their, ah, shortcomings). However, Napoleon was actually average height (5'5") for men back then, and the misconception sprouted from the fact he often posed for portraits with his Imperial Guard, who were all above average height; plus, the British were always looking for new ways to make fun of the French. This was compounded by confusion between French and Imperial units (by the French units of the time he was 5'2"; Imperial units were the same then as they are now) and the fact that he was nicknamed 'Le Petit Caporal' ('petit(e)' can be used as a term of endearment in French as well as meaning 'little' - a girlfriend is a 'petite amie', for example).
 * The Salem Witch Trials of 1692 never condemned any women to be burned at the stake. They were actually hanged; in addition, several men were convicted as witches, and one man refused to enter a plea, preventing his trial from starting, and was crushed to death under stones rather than give one.
 * That last gentleman continued to refuse to enter a plea, even as the pile of stones atop him grew.


 * In a related note, Arthur Miller's play The Crucible was based on a lot of testimonies from Salem, and did have quite a bit of accuracy- such as the story of Giles and the lack of burning. However, he also changed a lot of the facts for dramatic purpose (such as Abigail probably not having a sexual relationship with Proctor, who was in fact an 80 year old man). Although not as ingrained as some of the 'common knowledge' on this page, it has left a lot of people with inaccurate knowledge of the events.
 * The idea that during the witch hunts medieval Europe was a hysterical place where no-one was safe, and watching witches being burned or otherwise put to death was a common pastime in every village or hamlet. Do the numbers: 40,000-60,000 witches killed over 3 centuries comes to about one every second day - for ALL of Europe. Even given that the population was much less then, and taking into account that peaks would be considerably higher in some times and places, the average person probably thought even less about it than a person today would worry about getting killed in a traffic accident. The majority of medieval Europeans never saw anyone tried or executed for witchcraft.
 * Common Knowledge says the Spanish Inquisition was a brutal campaign that went from city to city rounding up heretics and executing them. It was actually very Fair for Its Day. Enemies were forbidden to testify against the accused, and evidence of witchcraft (and so-called "spectral evidence") was rejected. It was one of the first introductions of the "innocent until proven guilty" concept in its era (though the Inquisition's standard for "proven guilty" did allow for things that are forbidden in non-totalitarian societies today, such as confessions extracted by torture) and yearly executions numbered in the tens, not thousands.
 * The other inquisitions were even better, since "secretly being a Jew or Muslim" wasn't one of the things they were after—only heresies, some of which were pretty Path of Inspiration (Cathars, for instance, denied the validity of all contracts and considered it a sin to have children, because you were trapping spirits in flesh). Also, unlike contemporary secular courts (not just in Europe, either—China and Turkey used torture at least as much), the inquisitions only ever used torture as an interrogation method, not a punishment, and never as an execution.
 * Israelite Slaves did not actually build the Pyramids of Giza. They were not around until a few centuries later and more likely were responsible for the tombs in the Valley of Kings. It's doubtful at this point that there were any Israelite slaves in Egypt; little non-biblical evidence exists for the Jewish Exodus, and no archaeological evidence exists of Canaanite cultural adoption (since they were in Egypt for several generations) or a conquering group coming out from Egypt into Canaan. Given that, for most of its existence, the Kingdom of Israel was a client/buffer state of the Egyptian kingdom, the story may be allegorical in nature.
 * There is also a great deal of Values Dissonance since the ancient Egyptian system of slavery was very different from the more common perception of slavery based on the American system of slavery. Much of what was deemed "slavery" would in later times be considered indentured servitude or corvee labor.
 * Apes are not monkeys. Apes are related to monkeys on the evolutionary tree (humans in the Primate Hizzay!), and to be precise new world monkeys split off before the divide between apes and old world monkeys, so apes and modern monkeys may have had an ancestor that if it were alive today could be generally called a monkey, but apes (and this includes human beings, mind) are not monkeys.
 * Many people know all that, but use "monkey" anyway, with Rule of Funny as a justification. Similarly, "monkey" might be used to belittle an argument: "Do you expect us to believe that men evolved from monkeys?"
 * Depends on how you classify things. An argument can be made that all descendants of monkeys are in fact still monkeys. In particular, there's no trait common to all monkeys that is not shared by at least some apes, making any distinction rather blurry.
 * Some languages lack different words to distinguish the two. For example, in the Hungarian language, there is no single word meaning "ape"—they are called, in a word-for-word translation, "human-like monkeys". Same thing in French : "singe" is either monkey or ape. "Grand singe" or "singe anthropoïde" is often used for apes specifically, but just calling a gorilla "singe" is valid. Russian is similar.
 * This is also true for the English language. "Monkey" can be, and is, used as a generic term even by native English-speaking primatologists. That perhaps adds to the confusion as they will know what they mean when they're using the term "monkey" and a casual by-stander would almost certainly misconstrue the word.
 * Speaking of people who insist on using scientific-sounding words, "oxygen" isn't a synonym for "air". Only about 20% of the atmosphere is oxygen.
 * And going above that amount may cause oxygen poisoning.
 * The persistent myth that Albert Einstein was a piss-poor student is just that: a myth. Oh sure, his grades varied, just like every other student on the planet who isn't a Type A personality success-obsessive, but he wasn't a bad student across the board. When he lived in Germany, grades were marked one way (1 being very good, 6 being bad), but schools in Switzerland, where he lived later in life, used a different scale (1=bad, 6=very good). That's where a lot of the confusion seems to have arisen. The myth that he was bad at math specifically is as wrong as is possible; he was a prodigy in the field.
 * The closest this comes to being true is in his mundane arithmetic calculations. Like pretty much everyone, Einstein might occasionally forget to carry a one or misplace a unit (his genius is in the bold leaps he made, not in being an obsessive calculator) and his work was so important to him that he had contemporaries double-check those parts.
 * The myth that you don't use 90% of Your Brain is blatantly wrong. You use your entire brain, just not all at once, and the percentage you use at one time is between 15 to 25 percent. And no, you don't get magical powers if you somehow manage to use it all at the same time—that would actually be having a seizure. In early psychology (before access to imaging technologies like MRIs to see brain activity), the usage of a good portion of the brain was unknown, which isn't to say that we didn't use them, just that no one was sure quite what they did (now many of these areas tend to be associated with personality, self-control, planning, and memory).
 * At this time, the rough functions of pretty much every inch of the brain is known. Part of the myth also arises from the fact that only a small part of the brain is aware of what it is doing. Much of the brain is running "baser" functions. Imagine walking down the street while you spot and step off the curb without tripping, see an old friend, wave to them, and then talk as you continue walking together, happy to have seen an old pal. Most of your brain is running functions such as visual recognition, memory, language formation and processing, balance, coordination, emotional response, unconcious signals of your emotional state, and so on. You are only aware of the tiny bit of prefrontal cortex that is busy saying, "I!" A good analogy would be to compare it to a naive user who is using a GUI, unaware just how many processes are running deep beneath the surface of point-and-click.
 * Two of the most stubborn psychological myths are the above 10% and the idea that some people are "left" brained and some people are "right" brained. Experiments on people who have had their corpus callosum (the cords that allow the hemispheres to communicate) severed has shown differences in how the hemispheres work that has created the traditional definition (for example, someone may be able to draw something with their left hand, but only name it with their right), but not only is it not as cut-and-dried as people tend to believe (that the left hemisphere is logical, the right hemisphere is creative), there is no evidence of hemisphere dominance. Further, it has no association with handedness.
 * Another psychological myth is that there is a region of the brain associated with memory, and that damage to it would cause someone to forget everything. In fact, there are several regions associated with memory (since it's so complex), and damage to any one of them may result in retrograde or anterograde amnesia (inability to create new memories) along with a bunch of other memory processing and storage problems.
 * Contrary to popular belief, schizophrenia is not the same thing as Disassociative Identity Disorder (or, colloquially, Multiple Personality Disorder.) Also, OCD is not always about cleaning things and organizing.
 * Michael Jackson's "Billie Jean" was not the first video by a black performer to air on MTV.
 * The famous statistic that "1 in 4 women can expect to be raped". The original study was done in 1985 for Ms. Magazine, and included attempted rapes. Not only is it misstating the total number of actual rapes, but it was done over 25 years ago. Incidentally, according to the study, 1 in 6 men can also expect to be sexually assaulted, but that statistic is almost never brought up alongside the female one. The current version is down to 1 in 6 women, according to the National Violence Against Women Survey, "Prevalence, Incidence, and Consequences of Violence Against Women." That survey was published in 1998. Strangely, the numbers on men are down to 2%. That is, 1 in 50.
 * Vincent van Gogh...
 * ...only cut off part of his ear lobe, not his entire left ear. Perhaps not even that; recent evidence suggests that he lost the ear in a duel, then lied and said he cut it off himself because dueling was illegal at the time. Oh, and Rachel, the girl he was pining for and gave it to, was a prostitute.
 * ...didn't die by self-inflicted gunshot. He attempted it, but failed. He later died of his illness.
 * People will tell you that the idea of spinach as a source of iron is fallout from a nineteenth-century misprint... except there's no known primary source, and every study ever done has shown it and red meat to be reasonably close by mass ratio (although the iron in spinach is less bioavailable). The misprint, if it ever happened, must have listed an order of magnitude more than red meat.
 * Centripetal force is not just a "smarter" word for centrifugal force, which certainly exists, even though it's what's known as a "fictitious force." Centripetal force is the force holding an object to its circular trajectory when, from an exterior frame of reference, inertia would carry it off into space. The important distinction is that inertia is what keeps the water in the bucket over your head, not centripetal force, which is just the sturdy bucket keeping it from flying up into the air. Centrifugal force isn't the "equal and opposite reaction" to centripetal force, either, which usually affects whatever effects the rotation, or in the example above, you. Rather, centrifugal force is, from an exterior standpoint, the interior object's inertia, but from an interior frame of reference, indistinguishable (unless it's moving, which causes a Coriolis force as well) from a force pushing it to the outside. According to general relativity, the exterior frame is no "better" than this frame. Indeed, by the same standard by which centrifugal force is "fictitious," gravity, being a transformation of inertia, is "fictitious." Mocked in Xkcd here.
 * A good number of forces are by definition "pseudo-forces" in that they must be clearly defined as the composite of various other forces to be used. Centrifugal is by far the best known example (it's a construct of inertia in an accelerating reference frame, as mentioned above).
 * Gravity is still counted among the "four fundamental forces" because (apart from the Alliteration), "the three fundamental forces, plus this weird quality of space's geometry" takes too long to say. Leaving to one side that electromagnetism and the weak atomic force are probably the "electroweak" force.
 * Chameleons don't change color to blend in with the environment; they change color in accordance with their mood. Their default color scheme is already designed to blend in with the environment.
 * Many people believe chameleons change their color for the purpose of camouflage. Others reason it for mood. While social character of their ability to shift color pattern has of most importance, they use it to a lesser extend for blending too. Let's not forget heat regulation: darker colors are able to absorb more light, thus generating more heat, while brighter colors are able to reflect it.
 * Octopuses on the other hand, do. When one thinks about the ability to camouflage, the octopus is by far the best at it.
 * The U.S. Department of Defense was never called the Department of War. Until 1947 the U.S. had two separate cabinet departments for the armed forces—the Department of the Navy and the Department of War, with the latter agency controlling the Army. The Department of War became the Department of the Army in 1947 when it was combined with the Department of the Navy and the new Department of the Air Force into the National Military Establishment (NME or “enemy”). NME became the Department of Defense in 1949. The Department of the Army Seal even includes the words "War Office."
 * The belief that the introduction of guns rendered Samurai obsolete or Samurai in some way disliked guns. The Samurai were much more progressive with weapons and tactics than they are usually portrayed to be. They were the first group to use and develop tactics for guns. It never became a "traditional" weapon, but almost any Samurai who had access to firearms would be proficient with them.
 * The classic Japanese work on swordfighting, The Book Of Five Rings, even mentions tactics involving firearms.
 * On that note, it's also worth pointing out that traditionally one of the chief skill required of a samurai was actually archery and it was the role of archery that was lessened by the arrival of firearms not the role of the samurai itself.
 * Indeed, prior to the Edo period, a samurai's sword was his sidearm; their actual battlefield role was primarily horse-archers. Only after they'd thinned the enemy out with arrows would they dismount and fight any survivors on foot (they were essentially light cavalry but heavy infantry). Similarly, European knights' swords were their sidearm—their main weapon was their lances (they were heavy cavalry, distinguished by the size of the horse and the fact they performed lance-charges rather than archer-sweeps).
 * Glass is not a supercooled liquid, and it does not flow. Glass is considered an amorphous solid, which is why it melts under high temperatures. The reason some old windows are thicker on the bottom is because they were made that way (though not on purpose).
 * To clarify - glass thickness varied uncontrollably due to pre-modern manufacturing techniques. When glass arrived on a building site, glaziers would install it thick side down for maximum stability.
 * Another variation of the myth is that glass pipes bend over time - because bent pipes (existing due to the same techniques) were the last to be used.
 * The sky is not necessarily blue. It's occasionally midnight blue, black, pink, gold, purple, orange, etc.
 * Although presumably anyone who claims the sky is blue is aware of this, and is assuming the listener is also aware of this.
 * Ninja as oppressed peasants fighting against the samurai. In reality, most if not all ninjas were samurai, specifically trained in espionage, mercenary, and assassination tactics and hired by the daimyo against their enemies. Likely, this mistake is due to the fact that there was a number of rebellions of the peasants against samurai (especially in the at the time newly-conquered Okinawa, where most of the "traditional" ninja weapons stemmed from), and the fact that, despite popular belief, real ninja wore peasant clothes when doing their job, not the black pajamas that we often see (those were a purely theatrical creation inspired by the outfits of the kuroko, "invisible" stagehands in Kabuki theater).
 * The emphasis on ninja being primarily assassins or warriors is also largely incorrect. Espionage was far and away the most important and common task performed by ninja. Assassinations did occur, but they were fairly rare. When they did occur, poison was far and away the most common method used.
 * Ninja combat was largely focused on escaping from rather than killing opponents. The misconception that ninja were trained to easily dispatch multiple opponents is a slight misunderstanding of this. The main emphasis was to keep every opponent outside weapon's range while waiting for an opportunity to escape.
 * If someone were to create a real life Jurassic Park, they would need to alter the dinosaurs to fit the dozens of misconceptions caused by that film in order to avoid disappointing the public:
 * Velociraptors were two feet tall and covered in feathers. When Michael Crichton wrote the novel in 1990, Deinonychus, the five foot tall raptor-like dinosaur, was believed to be a member of the Velociraptor genus by the one researcher (Gregory Paul) whose book was used by Crichton as a reference, and this is stated in the novel. By the time the movie was released in 1993 this belief had been revoked, but Steven Spielberg kept the raptors at five feet tall because they liked the name so much. Some like to argue that the raptors in the films are really Utahraptors, a type of dromeosaurid discovered shortly after the movie came out, and are the appropriate size. In reality, Utahraptos were actually even larger. The lack of feathers is the result of Science Marches On, as feathered dromaeosaurid fossils had not yet been found and described at the time. There is also no evidence suggesting raptors hunted in packs, and while they were smart for dinosaurs, they weren't half as intelligent as primates.
 * While Deinonychus isn't actually a type of Velociraptor, it's still similar in form...and Velociraptor is a cooler name.
 * There is no reason whatsoever to believe Tyrannosaurus Rex was unable to see unmoving objects. Once again, the novel explains this by noting that many of the dinosaurs had the DNA of frogs spliced in, and that this frog species had vision based on movement. The film throws this out the window when Alan Grant claims that T. Rex as a species could not see unmoving objects. The sequel novel (but not the second film) pokes fun of this by having a character mock Grant's newest hypothesis, that a T. Rex would be confused by a powerful thunderstorm. Another freezes in the vicinity of a T. Rex... and still gets eaten.
 * Recent evidence has been discovered that T. Rex also was at least partially feathered...but so far the only fossils with feathers have been juveniles, meaning the feathers might fall out as they reach adulthood.
 * Dilophosaurus was nearly six feet tall (in reverse of the raptor situation) and did not have a frill or the ability to spit poison. Michael Crichton admitted this was an example of creative license, although he did get the size right in the novel—and didn't give it a frill; this was added for the movie, along with the size change, to make them more visually distinct from the raptors. More specifically, he stated that he outright made the poison spitting up in order to show how limited our knowledge is, because at the time it was purely from skeletal records, and thus there could be all kinds of things we don't know about dinosaur biology. The size meanwhile has since been handwaved by some fans as it being a juvenile.
 * But the biggest misconception related to dinosaurs has got to be how extinct they are. As any paleontologist worth their money will tell you, birds are actually a sub-group within Dinosauria (and have been seen as such for decades, with the rising fossil evidence constantly reaffirming the notion), and as any living person will tell you, birds are not extinct.
 * Many of the arguments used by marijuana legalization advocates are spurious, and sometimes just plain wrong. For example, the argument for medical use; people may have a case in wanting to ease their glaucoma, but when states do legalize it, many of the people who use it take it for "chronic pain" or "stress relief". In other words, they abuse the system so they can get high legally. Many legalization advocates would consider there to actually be nothing wrong with that, but those arguing specifically for medical marijuana probably aren't going to want it pointed out.
 * The "Twinkie defense" used by Dan White when he was put on trial for the murders of Harvey Milk and George Moscone is viewed in pop culture as the original Chewbacca Defense: people think White and his attorneys claimed that eating Twinkies drove him insane. In reality, the defense used his massive consumption of junk food, such as Twinkies, despite previously being a health nut, as evidence of his declining mental state. They didn't claim or even imply that the Twinkies themselves were a contributing factor.
 * The entire order of the Knights Templar were wiped out overnight is an example of the trope. The few that were not captured completely disappeared, which leads to many of the conspiracy theories related to them. Only a fairly small percentage of the French orders were actually killed and captured.
 * Most of the Knights Templar orders, especially those located outside France, were renamed or officially became part of other orders.
 * Many of the people actually arrested were arrested before the mass attack.
 * The members that disappeared most likely fled to Switzerland and aided the rebellion taking place there. While there is no official mention of the Templar, immediately after the Knight Templars officially disbanded, the rebels, which consisted of poor farmers with no education or support from any nobles, suddenly had large quantities of money, advanced weaponry, armor, displayed advanced military tactics, and both sides reported seeing a group of white knights aiding the rebels in a few battles. Even more odd because the only knights that would actually have a uniform appearance would be church orders, while the nobility and mercenaries would have their own coat of arms. In addition, the country founded afterwards was based on high military preparedness, secrecy, banking, and engineering and essentially operated exactly like the Knights Templar ran their own empire before being disbanded.
 * Not to mention that the Swiss flag, which first appeared not long after the Templars vanished, bears a distinct resemblance to a color-inverted Templar shield.
 * The use of the similarity between the Swiss flag and Templar symbol is actually an example of the trope. While the origin is not entirely known, it could not have been a color flipped Templar flag.
 * The symbol for the Swiss was a white cross, which was an extremely common symbol. White was selected to distinguish Swiss troops from other nearby countries. The red background was never actually selected. However, one of the founding cantons of Switzerland, Schwyz, used a red flag with no adornments. Originally, the white cross, the actual symbol for Switzerland, was placed onto Canton flags for a long time. The most common variant of the Schwyz flag places the cross off center, but this was not a consistent practice. In addition, the flag of Unterwalden, another founding canton, is red and white, so the white cross was placed in the red field. The actual flag known today didn't show up until 1889, as well.
 * In addition, it being a color flipped version of the Templar symbol is tenuous, at best. The Templars almost never used that shape cross. The cross wasn't the actual symbol of the order. The Dome of the Rock or picture of two knights on a single horse represented the order. The red cross was used on the battlefield because it was easy to identify and represented martyrdom. In addition, the Templars often used a white and black field, not just the solid white one normally identified with them.
 * The idea that the Templars were racist fanatics who wanted to commit genocide on the Muslims in the name of Christianity is what named the trope Knight Templar...only it isn't true. They eventually became more of a diplomatic organisation, doing business and trade with the Arabs, and helped introduce elements of Arab culture to Europe. The religious fanaticism idea was closer to the other crusader orders, who hated the Templars for their tolerance.
 * Senator Joseph McCarthy was never a member of the House Committee on Un-American Activities.
 * George Washington Carver did not invent peanut butter, although he did discover over 300 uses for peanuts.
 * The Titanic was never said to be unsinkable, the first mention of the ship being unsinkable is to be found in an article published the day after she sank and was basically meant to be a figure of speech.
 * Actually, it was.
 * The Titanic "unsinkability" claim is a bit difficult. Most of the claims that it was "unsinkable" are quotes from people, while most of the "official" uses of "unsinkable" add modifiers like "practically."
 * Wikipedia has a list of common misconceptions.
 * The salting of Carthage is not found in any source before the nineteenth century. It likely stems from confusion over a thirteenth-century bull, which called for a rebellious Papal city to be ploughed over "like Carthage," then salted as well, but in Carthage itself, only the first order is known to have been given.