Continuity Drift

A Plot Hole is something fans spend hours coming up with justifications for. Continuity Drift is something fans don't mind, but would probably spend hours whining about if it was introduced in an adaptation. This could be considered Adaptation Decay within the franchise Continuity.

Fictional worlds get very complicated. You have all kinds of Backstory, the political and social situation of the world, what kind of physics or Techno Babble there is, how magic works, and the overall atmosphere of the place. If you're writing about these, you probably didn't come up with the whole setting before you start writing. And if your work has more than one installment, you almost certainly didn't come up with it all before you started publishing.

So things change as you fill in details. What was unique becomes common, what was incredibly powerful becomes insignificant, and what was implied to have a wealth of unexplored detail... doesn't. After the story is fleshed out, exposition given way back in the beginning is off, somehow. Maybe the author thought that was how the world worked, but it didn't really turn out that way.

May be caused by the fact that Characterization Marches On. Sometimes the only way to keep sane is by treating the events you want to overlook as Broad Strokes. One specific type of this is Earth Drift.

Contrast with Retcon.

Anime and Manga

 * In Bleach, Aizen seems to be strangely misinformed about his Arrancar followers, labelling Grimjow's posse "gillians" when they had, in fact been adjucha before being turned.
 * Also, several cliffhanger moments picked back up with a character repeating the final few lines of the past chapter/episode/commercial break, only different. One such example of a sentence that started "Shinigami and a..." was changed to "Human and a..." a week later. This one sentence sent the fan speculation wild in the intervening week, as the speculated ending "Shinigami and a... Hollow" would be much more explanatory, but also a Voodoo Shark, while the "actual" sentence "Human and a... Shinigami" explains more or less nothing.
 * Although with this last one, if the new Fullbring type of character is to be believed,
 * In Naruto the naming conventions and other things of stronger ninjutsu are a bit different in the beginning. In the Wave Country arc, stronger attacks took a ridiculous amount of hand seals, with the water dragon one (B-rank) taking 42. After that, even the strongest techniques never used more than ten. Also, in the first arc most attack names were proceeded with "Ninpou (ninja art/technique): (name of technique)", which was dropped later.
 * Though that may have something to do with the skill level of characters increasing, The Water Dragon was used again later, though you may not have recognized it because he did it with just one handsign.
 * When Sasuke is with Suigetsu on his way to recruit Karin into their group, he speaks of her long-range chakra-sensing abilities as if it's something completely unique to her. Later, Killer Bee sees her sensing his location he refers to her as a "sensor-type", implying long-distance chakra-sensing is an ability other ninja can have, although probably a rare one (which is later confirmed when no less than three more of them show up two Story Arcs later, and an even later one has an entire division of an army made of them). In light of this, Sasuke's words come off as either misinformed or meaning her "unique power" was simply an individual and somewhat unusual version of it.
 * Naruto's own signature kage bunshin no jutsu (shadow clone technique) is an example—in the first story it gets treated as a dangerous technique and rare due to how much chakra it consumes, but it's later shown to be not all that special, although people with less chakra can't use it as effectively and Kakashi nearly makes himself pass out when he attempts to use it.
 * In Yu Yu Hakusho, Hiei initially points out that he and Yukina are half-siblings with different mothers. In the Three Kings Saga, it's revealed that the two have the same mother, were born at the same time, and Hiei was conceived by a man, while Yukina was conceived asexually.
 * At one point, in his introduction, Kurama says he's 300 years old. Later he claims to be a thousand.
 * In Pokémon Special an earlier chapter has Red capturing a Gyarados that already belong to another trainer (Misty). However, at a later point, Blue/Green says that, as is explicitly shown in most other parts of the franchise, catching a Pokemon some else has already caught is impossible.
 * The Pokémon anime also seems inconsistent at how many Pokémon a trainer could carry. An early episode features a trainer who carries plenty of Poké Balls at the time, shortly afterwards we're told they're only allowed to carry six. What happens to the seventh' has also changed. Ash's Krabby simply disappears soon after he caught it and gets sent to Professor Oak. But when he catches Sewaddle in Unova the Poké Ball simply shrinks down and becomes unusable until Ash sends one of his other Pokémon away.
 * In the beginning of Fist of the North Star, it is implied that Kenshiro and Shin are the only successors of the Hokuto Shinken and Nanto Seiken martial art schools respectively. This is especially notable when Kenshiro reminds Shin that they must cooperate and help each other passed on their martial arts to future generations. After Shin's death, it is revealed that the Nanto Seiken style has exactly 108 schools as other practitioners of the style are gradually introduced and while Hokuto Shinken had a clearly established one successor rule, there were other students of the art besides Ken himself who were not chosen for the succession.

Comic Books

 * In the pre-Crisis Superman comics, it's explicitly stated that Superman is the last son of Krypton. This is fine for a while... until Supergirl, Krypto the Superdog, and more start showing up. Someone once commented that Jor-El and Lara seem to have been the only people killed in the destruction of Krypton. That someone clearly never read the Superboy story that revealed they hadn't been, either. (And yes, if Superboy learnt this, then Superman should have known it all along.)
 * Hell, at least half of Superman's powers are the result of Continuity Drift and Power Creep, Power Seep. Originally he could lift a car over his head, outrun an express train, leap 1/8 of a mile, had telescopic vision and super-hearing, and "nothing but a bursting shell could pierce his skin". Later comics and cartoons gave him a long list of other/greater powers. The ones that stuck include the power to fly, the strength to lift ocean liners and move colossal space cruisers with his bare hands, enough speed to compete with the Flash in a foot race and (sometimes) make inter-stellar flights, super-breath/freeze-breath, invulnerability to anything other than magic or kryptonite, and expanded his vision powers to include x-ray vision, heat vision, microscopic vision, and the ability to see across the entire electromagnetic spectrum.
 * Even the origin of his superpowers changed within the years—as this page illustrates, Krypton was originally populated by Human Aliens that are more athletically evolved than the Earth humans, but eventually "The Complete Story of Superman's Life" was published, establishing that a Kryptonian can only gain super abilities on Earth, due to being born on a planet with heavy gravity and a red sun.
 * For his early appearances in Garfield, Nermal was owned by Jon's mother. Now he just wanders in whenever needed.
 * Similarly, Odie used to belong to Jon's friend Lyman. After Lyman vanished, Odie became Jon's pet. Some fans believe digging up Jon's back yard could be... enlightening. Word of God on the issue is "you don't want to look in Jon's basement".
 * One of the stories in Garfield: His Nine Lives is an alternate history of Odie being bought by Jon as a companion for Garfield.
 * In Strontium Dog, the term 'strontium dog' was originally an insult, and in an early strip, Johnny forced his client to pay him a higher fee after they refer to him as such. After a year or two, nobody seemed to care—Johnny referred to himself as a strontium dog, as well as his fellow bounty hunters.
 * Marvel's Namor has the following as his current powers: Hulk-level super strength, flight, amphibious physiology, and a bad temper. When he was introduced, and well into the sixties, he could also talk to fish and mimic the abilities of any undersea creature, including puffer fish. No one really talks about these powers, but it's possible he only doesn't use them because it would make him look stupid.
 * In Judge Dredd, Judges seem to have originally been portrayed as an elite unit within the regular police force, and some early strips feature non-Judge cops as Red Shirts. Nowadays, the entire police force is composed of Judges.
 * The first published Judge Dredd comic describes Dredd as operating in New York City and as having been elected to his post. Later, New York was revised to just part of Mega City One, and Judges were presented as having passed through an intense years-long training program before being graduated to duty with no election necessary. It could be a case of Fridge Brilliance—they ran out of Red Shirt regular cops and/or realized that they can't do the job, so you don't see them any more.
 * If you're a Fables fan you'll notice this happen often. Legends in Exile has a lot of differences to the later books. The community is suggested to be much larger, Beauty and Beast requiring a carriage to attend the annual Remembrance Day ball, yet by March of the Wooden Soldiers we can see that Fabletown is just a single, small street with a few hundred residents, most of whom live in the woodland building.
 * It's possible they just rented out a mansion/hall for the event, being it reminded them of home, and just made sure only Fables staffed it.
 * Green Lantern ran into this very early on in the pre-Crisis comics with his origin story. In his first appearance, Hal Jordan became the Green Lantern after he was given the power ring by a dying alien, whose spaceship had crashed on Earth. Makes perfect sense...until we learn that a Green Lantern can travel through space with only their ring, and that no one in the Green Lantern Corps uses spaceships for this very reason. Interestingly, the 2011 live-action adaptation makes a point to rectify this scene—Abin Sur is dropped into an escape shuttle during the battle in which he is mortally wounded.
 * This was explained in the story "Earth's First Green Lantern" in GL #16 in 1962. The spaceship was part of Abin Sur's plan to trick a body-possessing alien, by deliberately having his ring run out of power. The alien would then assume he wasn't a threat and he could recharge the ring and defeat it (the alien didn't know about recharging).
 * This was later tackled in the 80s by none other than Alan Moore (and repeated in Geoff Johns's "Green Lantern: Secret Origin"): Abin Sur had been told a prophecy that said his ring would fail on him when he most needed it, so he began using a ship so that his ring wouldn't shut off in mid-space flight. Unfortunately, since the ring needs willpower to function, losing one's faith in it—or yourself—is exactly what makes it not work, therefore making the prophecy self-fulfilling.
 * The Clone Saga was filled with this:
 * A few issues after the original clone story was published, there was a story that revealed that the Spider-Man clone (later named Ben Reily) was a partner of the Jackal (the initial villain mastermind behind the Clone Saga) who had been turned into an exact clone. This revelation was brought on by the High Evolutionary, a man who was on the level of Reed Richards or Doctor Doom. When Marvel Comics brought the clone back, they had a quick throwaway line that the High Evolutionary was jealous and lied. This means that the Jackal, a B-list villain and lowly university professor, had somehow managed to one-up a man who had made himself as powerful as Galactus.
 * Many new clones were introduced as being made before Ben Reily, making him much less special.
 * Readers were subjected to this within the saga itself. The story also introduced a mysterious villain named Judas Traveler who was a mystic that had a wide variety of powers including Time Travel. The writers had no idea who this villain was, nor did they know what to do with him. It was eventually hand-waved that he was a mutant with the ability to cast illusions which set up many plot holes since the man was nearly omniscient.
 * The story was also responsible for bringing back Norman Osborn from the dead. Not only did this slap a huge Retcon on a story that was written 20 years earlier but it negated the actions of the Jackal throughout the Saga.
 * Very early in Preacher (Comic Book), Cassidy survives being shot by the Saint of Killers. A vampire surviving being shot is no big deal, but we later learned that the Saint's guns were forged by Satan himself from the Angel of Death's sword and made so that they will never miss, never run out of ammo, and always kill whatever they hit. The first thing the Saint does with them is shoot the Devil in the face, and at the very end of the series . Garth Ennis later admitted that he didn't realize where he would eventually go with the Saint, and we should just try not to think too hard about that early encounter or why Cassidy survived.

Film

 * Star Wars: The prequel trilogy was written many years after the original trilogy. Some implications in the original trilogy don't seem to mesh very well with what the prequel trilogy reveals. The possible explanations for these rifts vary in how far-fetched they are.
 * When watching the original Star Wars trilogy, one gets the impression that the Empire has existed for a long time. The prequel trilogy, however, shows that it's only nineteen years old. For example:
 * Admital Motti dismisses the Jedi Order as an "ancient religion" and Han Solo sees The Force as superstition, suggesting that they never even saw a Jedi firsthand in their lives. However, 19 years ago they were a major force in the center of the Republic. It's possible that the Jedi were such a small order compared the to the size of the entire Republic that they were considered somewhat legendary long beforehand. Empire propoganda/censorship might also have helped undermine their legacy, as would the destruction of the Jedi, the Republic's primary historians.
 * Tarkin announces the dissolution of the Senate as having swept away the "last remnants of the Old Republic", implying that the Senate had long been a powerless organ of a long-defunct government. The opening scene illustrates how meaningless the Senate is when Vader boards and captures Leia's ship.
 * When Vader tells Tarkin that Obi-Wan is aboard the Death Star, Tarkin says, "Obi-Wan Kenobi? Surely he must be dead by now." Vader replies, "Don't underestimate The Force." This implies that if Kenobi weren't a Jedi, he likely would have died of old age by then. The prequels set Kenobi as no older than his 60s during A New Hope, hardly an improbable age. However, Tarkin might have assumed that Kenobi wouldn't last long as a defeated refugee living under a rock. Also, Vader's reply could be asserting the accuracy of his Force senses rather than the Force's power to prolong life.
 * Obi-Wan says, in Return of the Jedi, "When I first met him, your father was already a great pilot, but I was amazed at how strongly the Force was with him." It's technically accurate, but surely he would mention Anakin was already a great pilot at the age of nine? But that detail didn't exist at the time.
 * Obi-Wan addresses Vader as "Darth", having earlier referred to him as "A young Jedi named Darth Vader", implying that "Darth" is his first name. The prequels show that it's actually a title, akin to Vader calling Obi-Wan "General" or "Master". In retrospect, the scene works very well if we declare that Obi-Wan is making a point out of refusing to call Vader by his name.
 * Ben also says in The Empire Strikes Back that Yoda was the Jedi Master who instructed him. Yet in Episode I, He's the padawan of Qui-Gon, not Yoda. In Episode II, Yoda is shown teaching a large class of younglings, implying that Yoda gives some training to many or all Jedi (a fact made explicit in the Star Wars Expanded Universe), but it's still not appropriate to say that Yoda was the Jedi Master who trained Kenobi.
 * In A New Hope, Obi-Wan makes it sound like Anakin Skywalker and Owen Lars had a long history together, saying things like "[Owen] didn't hold with your father's ideals" and "He thought [Anakin] should have stayed here and not gotten involved." Then in Attack of the Clones, we learn that the two aren't even blood relatives, and they only met each other once. Briefly, at that. They were originally intended to have been brothers, but this was changed (obviously).
 * The Star Wars Expanded Universe also seems to contradict the films occasionally.
 * In the introduction to the novelization of A New Hope (whose title is just Star Wars, of course), it is explicitly stated that the Emperor is a powerless weakling who is controlled by his Evil Advisors. According to Wookieepedia, the Whills got the whole story from R2-D2 about 100 years later, so I guess that means that every one of the main characters is now an established liar.
 * The opening crawl of A New Hope states that "Rebel spaceships, striking from a hidden base, have won their first victory against the evil Galactic Empire." manages to mostly remain true. All prior victories were before the Rebel Alliance's foundation 2 years prior to the film, not against The Empire (The Star Wars d6 module Domain of Evil) or ultimately part of the campaign to steal the Death Star plans in the first place (Empire At War).
 * The lightsaber itself started as a ceremonial weapon, mostly used for battles between Jedis and a last resort weapon when diplomacy failed. Twenty years of expanded universe, parodies and video games later, Jedis are facing off entire armies with nothing but a lightsaber.
 * The Force Ghost technique was implied in the original trilogy to be the standard Jedi afterlife (at least for talented ones). Even Anakin achieves it when he dies after his Heel Face Turn. By the time new Expanded Universe material and the prequels came out, it was established that this technique was extremely difficult to perform and that Qui-Gon Jinn was the first to use it, and that Yoda and Obi-Wan learned it from him.
 * Ice Age was set during a real ice age with humans. The newest one has more anthropomorphized animals and no humans.
 * And now dinosaurs!!
 * Humans were extremely rare when Ice Age takes place, so it's possible they just never crossed paths.

Literature

 * The first Redwall book kind of implies that there are humans around somewhere. It suggests the standard rules for talking animals (they just don't do it in front of people except for maybe one kid who has magical adventures with them, and let's ignore the implications as far as livestock are concerned), but this all goes away from the second book on. It is also implied that the humans are much larger and may not understand them.
 * Harry Potter:
 * The kitchens moved. Rowling intentionally wrote a bit in the first book saying how the layout of Hogwarts is constantly changing specifically to cover for this sort of thing.
 * The points are worth a lot more in the first Harry Potter book—Harry and company are mortified at the prospect of losing 50, let alone 150 points, but in a later book, Snape docks 50 points with only a passing mention. Steve Kloves (or Chris Columbus) tried to mitigate the point thing in the first movie. At the end of the first Potions lesson (the part left on the cutting room floor), Snape takes five points from Gryffindor whereas he only took one point in the corresponding scene from the book. (By the later books, taking five points had become the standard response to a minor infraction.)
 * And under normal circumstances, the older students probably wouldn't have minded the point loss. But as there was single House winning the House Cup year-after-year and the older students saw that there was a chance someone else might win for a change. Then on top of all this, Harry had it particularly bad. He was the famous Boy Who Lived... who also happened to be the Quidditch Hero that made the win seem possible. And then he turns around and does something stupid. After winning this year, it probably went back to normal where only the first through third years really even care about points.
 * In the first book, Hagrid describes the deaths of Lily and James as if they hadn't been actively against Voldemort already, and it was a mystery why he would even be bothered to kill them if the opportunity came up. In the third book, Fudge, telling the story of how Voldemort found them, mentions that it was "well-known" Voldemort had been seeking the Potters at the time, with Hagrid right there, and by the fifth, we learn that they served alongside Hagrid in the eponymous Order of the Phoenix the first time around. The effect is that in that first scene with Harry, Hagrid lied... a lot. The movie corrected this also, taking out the questioning of why Voldemort went after Harry's parents and having Hagrid simply say "your parents fought against him, but nobody lived once he decided to kill 'em."
 * Hagrid may have been softening the blow for Harry, considering that in a half-hour period, Harry learned he was a wizard, that would be leaving for a new school the next day, that his aunt and uncle had lied to him his whole life about pretty much everything, that he's special, that he's famous for the tragedy that kicked off his life with the Dursleys, that there's a whole other world out there he was unaware of, and so on.
 * In Goblet of Fire, the Death Eaters who tortured Neville Longbottom's parents into insanity are charged with having assaulted "an auror and his wife," which certainly implies that Neville's mother was not herself an auror. By the next book, however, Rowling had apparently decided that both of Neville's parents should have been aurors, making the phrasing of the charges in the previous volume extremely difficult to justify without positing a degree of sexism not otherwise evidenced in Rowling's wizarding world.
 * In later books, you need only to say "Riddikulus" to beat a boggart. The whole "make it funny" part is abandoned after the third book.
 * Discworld: In the words of Pratchett, there is no Continuity Drift. There may, however, be "alternate pasts". In other words, A Wizard Did It, probably by accident while trying to do something else.
 * And then the history monks, also known as the Men in Saffron, had to come by and try to sort it out as best they could. The classic "bug" is that the two major playhouses in Ankh-Morpork are the grand Victorian-era Ankh-Morpork Opera House from Maskerade and the shabby Elizabethan-era theater The Dysk from Wyrd Sisters, an obvious case of Anachronism Stew, especially since the Dysk was built in Wyrd Sisters "a new type of building", and the Opera House has a history stretching back decades.
 * The Colour of Magic has references to the "other lords of the Circle Sea", and implies that Ankh-Morpork is simply the biggest and most crime ridden of many dangerous city states in the region. Later books show that the other 'cities' are peaceful, rural backwaters. The same book implies Ankh and Morpork were separate cities, a point that is never restated.
 * It's implied in other books that they had once been two cities that had merged, and the old dividing line was the Ankh river.
 * In the early Discworld books, Lord Vetinari comes off as an overweight Smug Snake, but in latter books, he morphs into the thin, perpetually-gaunt master-manipulator we know and love. Fans have attempted to explain this away by stating that it was a different Patrician of Ankh-Morpork, but Word of God has stated that this is not the case.
 * Same goes for Granny Weatherwax. In Equal Rites, her constant accomplice Nanny Ogg is nowhere to be found, she only wears her pointy hat when necessary, and she actually lets someone interrupt her without reprisal. It took a couple of books before she metamorphosed into the walking Crowning Moment of Awesome she's known to be.
 * Equal Rites mentions the existence of Magicians (essentially failed students who are reduced to being lab assistants to proper Wizards) and Thaumaturgists (untrained dogsbodies who go and fetch dangerous spell components such as "the semen of a live tiger"). Neither are ever heard of again despite several books focusing pretty heavily on the Wizards.
 * It seems pretty clear what's happened to the magicians, thaumaturgists, and possibly warlocks—they all work as the Disc's "scientists" in the High-Energy Magic Department. Since High-Energy Magic has proven that dangerous spell components (or, indeed, any spell components at all) are often not necessary, their previous role becomes redundant, and they end up working there instead, where less magical skill is required.
 * A minor example: Nanny Ogg's Cookbook (1999) has a bit in the courtship section about sending coded messages by the positioning of stamps on a love letter. Nanny views this as a bit old-fashioned, from the days when "a girl wasn't expected to have any private correspondence until she was thirty-five." In Going Postal (2004), Moist von Lipwig invents the postage stamp.
 * Possibly Nanny was referring to how the stamping of a letter was oriented, rather than to stick-on paper stamps. Going Postal did show that old-time letter carriers had to rubber-stamp a letter to prove that its delivery had been paid for.
 * A lot of the Ankh-Morpork related inconsistencies are because the city was originally a Lankhmaresque generic fantasy pastiche. As it became more unique, a lot of the original characterization was dropped. In The Colour of Magic, it's much more of a Wretched Hive than the borderline-Steampunk City of Adventure in the later books.
 * The Dark Tower:
 * In the original version of book I, Roland discovers that the Man in Black he's been chasing isn't Marten but Walter. Later books in the series indicate that Marten, Walter, Flagg, and so on are the same adversary Roland's been chasing all this time, not just symbolically as "the Man in Black" but literally the same person. This is made explicit in the revised version of book I.
 * In book II, Eddie Dean is from Co-Op City, The Bronx, in 1983. From book III onward, he's from Co-Op City, Brooklyn, in 1987. This would be a simple gaffe, if not for the fact that it becomes a plot point that Co-Op City really is in the Bronx and Eddie's Co-Op City in Brooklyn is a sign that his world isn't the "real world".
 * There are tons of minor changes as well. For example, it seems like Roland's motivation for going to the Dark Tower changes every book as does the function of the Tower itself. Hell, Roland attributes the multiverse's imminent collapse on the Tower itself at the end of book IV. It's not until the last three that everything finally solidifies, probably due to King finally deciding what the Tower is and does.
 * At the end, this may be justified due to
 * King can't seem to make up his mind exactly how old Eddie and Susannah are. In one book, Eddie is twenty-three; in the next, he's "nearly ten years older" than Jake, who is consistently said to be eleven. This might be related to the aforementioned confusion over what year Eddie left his world. And in the third book, it's mentioned that Susannah is three years older than Eddie, while the second book implies that the age gap is much greater.
 * In the original version of book one, the Final Boss is referred to (in a very sinister manner) as The Beast. Turns out they meant the Crimson King all along,.
 * The most obvious bit of Continuity Drift in The General series is the way Lady Suzette's eye color and the number of generations her family have been patricians vary from book to book.
 * Pick any two Oz books by L. Frank Baum and then work out a coherent history of that country and its populace.
 * This is lampshaded in Wicked, where Elphaba and Boq are searching through documents in their school's library trying to piece together the origins of Oz, and everything they find is confusing and contradicting.
 * Animorphs has several:
 * Quite an infamous one among fans is that one of its shape-shifting heroes uses the telepathic communication they speak with while in animal form when he's in his normal human form. Every book afterwards features "thought speak" as only being functional when they're in bodies other than their own. K. A. Applegate (the author) herself has flat-out admitted that it was a mistake. The fan nickname for the incident and others is KASU, an acronym for "Katherine Applegate Screws Up/Screw-Ups". An extensive list can be found here.
 * There are also minor ones, such as the Yeerk naming system. At first, not just Visser but all names are treated as ranks, with at least three "Iniss [some number here]" people, with the You Have Failed Me... victim among them serving as a reminder to The Dragon Iniss 226/Chapman that even "an Iniss of the third century" is expendable. A later Yeerk had had his number lowered as part of an advance in rank. After these early examples, no two non-Visser/Sub-Visser Yeerks will ever have the same name, or have attention called to their designation. Vissers' names before they were Vissers are considered their "real names" and are never "[Word here] 1."
 * We get bits and pieces of the Ellimist's backstory throughout the series... then the Ellimist Chronicles comes along, ignoring all of those bits. However, Marco mentions more and more leading up to it that "we don't know if he's one guy or part of a group." (When we first met him, he explicitly calls the Ellimists a group more than once. Some time after the last time, Marco decides it's a question for some reason. Then it turns out he's one guy—whose story has little in common with the hints given in the series proper.)
 * Although it is established in the Ellimist Chronicles that at some point the Ellimist  making it entirely plausible for him to refer to himself as a group.
 * He could also be ...a liar. Ellimist Chronicles was just him doing a favor by telling the truth for once.
 * Related to the first KASU (a term KA actually uses sometimes!) is Ax's use of thoughtspeak in human form. At first, he mentions that as a human he must now use human speech. Eventually, though, he begins using thought speak in human form to talk privately with the other Animorphs. As human form is a morph for him, he still has it there. Apparently, he just... never thought to try it for over 30 books?
 * Also, early on, thought-speak could send imagery and feelings as well as just words. This goes away fairly soon, though.
 * Whether "War Prince" is the rank after "Prince" or simply the full title and used with it interchangeably changes back and forth.
 * Crayak is a "he" until his very last appearance, then becoming an "it."
 * If you want to get really picky, when Visser isn't used as part of someone's name, is it capitalized or not? Visser Three is "the Visser" for a very long time, then becomes "the visser." Considering his temper, you really want to get his title right!
 * Early books seem to imply that the Yeerk homeworld is part of the Yeerk Empire—Visser One was apparently stationed there before visiting Earth in book 5, and the future Visser Three tries to use the Time Matrix to escape there in The Andalite Chronicles. However, The Hork-Bajir Chronicles states that the Andalites blockaded the planet soon after the war started, and the Yeerks still on that planet have no contact with the Empire; neither visser would even be old enough to have been born there. Maybe Visser One was in charge of some effort to reconquer it or something, but why would Visser Three try to flee to a planet where his enemies are in control? Even with an Andalite body that seems like a pretty big risk to yourself and your new, incredibly-valuable super-weapon.
 * Early books seem to imply that the Yeerks had conquered numerous species; the Yeerk controlling Jake, for example, lists a couple random ones to imply how mighty the Empire is. Later books, however, never bring up any (totally) conquered species other than the Hork-Bajir, Taxxons and Gedds.
 * Kir Buluchyov's Alice, Girl from the Future series was notorious for this. Most notably, Krys (the Rat) a recurring villain, went from being a spider-like alien who changed shapes thanks to a holographic projector to a humanoid alien who changed shapes without explanation to a rat-like alien who changed shapes thanks to special pills. As Buluchyov himself admitted in an interview late in life, this was due to the fact that he didn't like to re-read his books.
 * J. R. R. Tolkien's The Hobbit is a prime example—it was rewritten at least three times to fit in with the wider Middle-earth mythology (e.g., in the first draft, Bilbo mentions the possibility of going to China). Even then, some incongruous details remain, like a talking purse, mountain giants playing catch with boulders, and magical boots that fasten themselves (invented by Gandalf). Tolkien also had the gall to say the earlier account of Bilbo getting the One Ring was a lie. The later and truer account was later written down after Gandalf questioned Bilbo about the ring.
 * His son, Christopher Tolkien, wrote in the preface to The Silmarillion that he had a devil of a time editing his father's as-yet unfinished material into something internally consistent, because the Continuity Drift was so bad. But then again, it was unfinished, largely because J.R.R. kept going going back to the beginning to revise it.
 * The James Bond novels suffered from this. It's pretty much impossible to reconcile Bond's history as given in Casino Royale with his obituary in You Only Live Twice, unless the British secret service was in the habit of sending teenaged schoolboys out to conduct elaborate coups against the Bulgarians at the gaming tables of Europe. The Young Bond series of juvenile novels have done an excellent job at explaining away some of the inconsistencies (such as making his first car a gift from a dying uncle he received while still a teenager).
 * In the Vorkosigan Saga, in Warrior's Apprentice, it says that Vorhalas' sons were on the wrong side of Vordarian's Pretendership, whereas in Barrayar one is angry because the other was executed for dueling.
 * The angry surviving brother is strongly implied (maybe outright stated?) to have had Vordarian's backing . The duellist's fate might be pure drift, or might not: a lot of Apprentice is driven by Miles' parents' generation obfuscating some of the ugly details of that time period. It's quite possible Aral told Miles "he was killed in the civil war" in lieu of "he was executed for getting drunk and murdering his friend". (And also, much of the first part of Barrayar was apparently written before Apprentice.)
 * Alan Dean Foster's Humanx Commonwealth series started off the character of Flinx as a partially telepathic young thief, with the implication that his powers, though unusual, are not particularly terrifying and bizarre. The two mentor figures, Bran Tse-Mallory and Truzenzuzex, even comment among themselves that the boy is "a partial telepath", but apparently don't care enough to research the matter further. In later novels that expand Flinx's origin story, it's revealed that he's an empath, not a telepath, and was created as such by a universally reviled group of Evilutionary Biologists, so they really ought to have been more curious. Also, Flinx's age given in Bloodhype conflicts with the universal timeline Foster later established, the description of his ship is vastly different (to the point where Foster retconned it to be able to camouflage and reconfigure itself at will), and his pet minidrag is male, rather than the female it was established canonically to be in the chronologically earlier The End of the Matter.
 * Older Than Television: For continuity drift within a single book try Kenneth Grahame's The Wind in the Willows. The relation between the anthropomorphic animals and humans changes between chapters. Initially the two groups are entirely separate, with the animals mostly ignorant of humans and their culture. Then Toad turns up, with his house, his ability to buy cars, and suffer under the criminal justice system without anyone noting his amphibian nature.
 * Warrior Cats has this as well. At first, battles were a lot more common and weren't treated nearly as seriously as they are in later books. In later stories, an border skirmish is a big deal and cause for concern about Clan wars, where in the early books it was the standard response to finding a trespasser: fight first, ask questions later. ShadowClan driving WindClan out in the first book was taken seriously, but if that happened in later books it would have been an instant Moral Event Horizon rather than the other Clans just raising a slight protest over the aggressiveness of the action.
 * Empire of the Ants by Bernard Werber started out as a story among ants communicating with each other, where Humans Are Cthulhu. 327, a male ant, witnesses dozens of ants being killed at the same time by an unknown enemy, and asks other ants about it. A yellow ant tells him that he once saw several ants being killed like this, while crashed by a pinecone, and is described as "laughing" as this is "yellow ant humor". In the sequel books (Day of the Ants and Revolution of the Ants), though, the ants are described as not knowing what humor is and the humans have to describe it and teach them.
 * In Tom Holt's first J.W. Wells & Co novel, using the eponymous Portable Door for more than an hour is incredibly draining, with potential risk to the user's life. By May Contain Traces of Magic, a character has pretty much relocated to his past (our present) using said Door, and isn't even remotely drained.
 * In the first few Honor Harrington novels, Harrington is described as winning in hand-to-hand combat due to her practice in martial arts and coming from a heavy-gravity world, while her deadly accuracy in a duel is due to single-minded relentless practice at a range. Later books and short stories in the series reveal that she's come from a family that's had some pretty extensive genetic engineering, giving her enhanced physical abilities that would have played a role.
 * Constance's eye colour in The Book Of The Dead changes from violet to blue to "dark" over the course of the novel.

Live-Action TV

 * Charmed, after the Wizarding School was introduced. In later seasons, they get all obsessive about protecting the Wizarding School because "where else will the children learn about magic?", even though none of the other magical characters shown in the show up to that point went there.
 * On Buffy the Vampire Slayer, while it was only All There in the Manual in the first place, The Master was originally supposed to be 600 years old, and to have outgrown human features as a result of his age. However, a flashback showed him siring Darla approximately 400 years ago and looking the same, even though if he'd already stopped looking human at 200 Angel and Darla should have had the same look by the time of the series. The comics presented an alternate explanation for his appearance—while at the same time establishing him as at least 800 years old. And this explanation clashes with the similar Looks Like Orlok appearance of vampire called the Prince of Lies over on Angel.
 * In the first few episodes of Roswell, it's clear that all the aliens have all the powers, but Michael just isn't as good at using them. We even specifically see Michael heal someone's broken ankle. As the series went on, this drifted into them each having unique special powers to the point where Max being the only one able to heal people became a huge thing. This was presented as the way things had always been. This is most likely because the series started out sticking to the book series it was based on (where all of the aliens had the same broad range of powers), but soon developed into a completely different story line with the six main characters being the only thing consistent with the books.
 * CSI has this, mainly with the character of Grissom. In the early episodes, he is shown to be a quirky eccentric with lots of connections. However, by the next season he is a reclusive intellectual with traits of Asperger's.
 * In the first season Lost episode "Raised By Another," a flashback shows Claire fretting that her mother will disown her if she tells her she's pregnant. The third season episode "Par Avion" reveals that Claire's mother was in a coma at the time.
 * The Adam and Eve skeletons introduced in season 1 are implied to be 50 or so years old and we're left with the impression that they were some loving couple who died on the island. In season 6 we discover that the skeletons are hundreds of years old and belong to the smoke monster's original form and the crazy lady who pretended to be his and Jacob's mother.
 * Aaron and Walt's importance. Season 1 and season 2 make a point foreshadowing Walt's powers. It's a non-issue in his few appearances in the later seasons. Aaron's destiny was hinted to be fairly important when the psychic warned Claire he must not be "raised by another". He gets raised by another (Kate) and there seems to be none of the dire implications the psychic hinted at.
 * There are some differences between how the Others act in early seasons compared to later on, which can be chalked up to the fact that the writers hadn't really decided what the Others were yet. In early appearances it seems like they were intended to have supernatural powers, most notable in Ethan's super strength and ability to pop up from out of nowhere. And while we're on the subject of Ethan, in season three Ben says that Ethan was their surgeon. Now, why would Ben send the Others' only surgeon on a dangerous mission to infiltrate the crash survivors (as he did Goodwin, who it seems he sent with the intention of getting him killed) a short time after he has found out that he has a lethal tumor on his spine? Also, in the first few seasons it was well established that the Others kidnap children, and we assume that this was the reason they took Rousseau's daughter, Alex.
 * There's also the fact that Ethan is apparently one of the few who grew up on the island, which makes you wonder where he got his surgeon skills. Of course, considering that the whole surgeon thing is from a throwaway line in "Stranger in a Strange Land", perhaps we should just forget about it. And you have to wonder about the Others not kidnapping Jack and co when they went after Michael.
 * When Kate goes to see her mother in "Born to Run," Diane Austen doesn't seem to recognize her and starts screaming for help. The effect, especially given Kate's surprised and heartbroken look, suggests a failing memory. A later episode ("Left Behind") establishes the reason for Mama Austen's behavior when Diane warns Kate "if you ever visit me again, I will scream for help" due to what Kate has done. It's a valiant effort, if not altogether convincing.
 * Actually watch "Born to Run'' again. When Kate approaches her she says "Mom, it's me. It's Kate." Her mother asks "Katherine?" right before she screams for help.
 * An early Babylon 5 episode has Delenn mentioning that Minbari society is made up of two castes: warrior and religious. Later episodes show that there is also a worker caste, which becomes very important when the Minbari start a civil war. Word of God says "She just forgot to mention the worker caste. That's my story and I'm sticking to it." Just how often the other two castes forget the worker caste eventually became an important plot point. The in-canon novel "To Dream In the City of Sorrows" goes into more detail about the marginalization of the worker caste: there was an objection to them joining the Rangers, members of the other two castes would lose face if they spoke in worker dialect, and before Valen came there wasn't even a pretense of them being an equal caste.
 * Star Trek has several, with the fans being far more forgiving of some than others. One essay calls these "Brain Bugs" and posits that it's because of a long succession of writers either being unfamiliar with or flat-out misunderstanding what came before and as such, end up simplifying concepts and reading unintended meaning into minor details. Examples include:
 * Deanna Troi went from sensing people's emotions to outright experiencing them.
 * Q being several different beings with the same face (never actually stated, but it was the idea the writers had and the actor's performance in the TNG pilot bears it out).
 * In the original pilot episode, the idea of Vulcans repressing emotion and acting on logic hadn't been thought of, and Spock seems to be a very different character because of it. While one could easily argue that the pilot episode is non-canon, the TOS episode "The Menagerie" was a Whole-Episode Flashback to it. It also implied that faster-than-light travel was a new invention, when it was later established to have been invented much earlier.
 * In TOS, the most common time-reference was that it was set about 200 years after the 1960s. Furthermore, there had been nuclear warfare on Earth after the 1960s. So it actually made some sense that warp drive, as of the time of Pike's first visit to Talos IV, would be a fairly new thing. (It also implied that some form of FTL travel existed other than warp drive, maybe natural gates or something, because of the Valient in "Where No Man Has Gone Before" and the Romulan War. But all this kind of worked, because it gave the feel of a frontier, worlds not settled all that long, technology advancing but with the backwaters behind. TOS just simply does not fit, continuity-wise, with the other series.
 * The hand-held communicators got larger between Enterprise and TOS, before shrinking to com-badges in TNG.
 * The original series was very vague and contradictory about what century it was supposedly taking place in—offhand references implied the 22nd, 23rd and even the 28th centuries. The Wrath of Khan finally cemented the setting as being in the 23rd century, though the exactly 300 years in the future detail was established later.
 * Most of the well-known races in Trek are wildly different from how they were originally conceived, beginning as a complex race and devolving, from one writer to the next, into a Planet of Hats. The Ferengi, in their first appearance, were being set up as a fairly major military power; a few seasons later they were a much smaller power and quite cowardly, and by the time of Deep Space Nine, they were, for all intents and purposes, not a power at all, and their personality had withered down to all profit all the time.
 * In that case, the effect was inevitable. The Ferengi were never scary, they came across as more-than-slightly ridiculous from their first appearance, and their capitalism and obsession with dressed women came straight out of Gene Roddenberry's personal fixations, which the first two seasons of Star Trek: The Next Generation served as a showcase for.
 * Similarly, the Borg were, initially, all the same organic race. In the first episode they are introduced, incubators with Borg young are shown, and assimilation is used only in the sense of acquiring alien technology. In "The Best of Both Worlds", they kidnap and assimilate Picard to act as a liaison to humans—but this is done surgically and with one particular purpose in mind. By the time of First Contact (and their subsequent appearances on Voyager), they don't reproduce or even conduct scientific research of their own at all, relying on assimilation alone for both.
 * One Voyager episode showed some Borg children who had come out of their development chambers early and so were only partially assimilated. It's possible that children who are assimilated are kept in the incubation chambers until they reach maturity, for whatever reason.
 * In "Space Seed", Spock refers to the Eugenics War, which occurred in the 1990s, as World War III, whereas later episodes and spin-offs establish WWIII as taking place in the mid or late 21st Century.
 * In several early Ferengi episodes, Troi claims to sense their feelings. Later on, Ferengi are immune to telepathy/empathy.
 * Klingons started off as a stand-in for the 1960s Soviet Union and were generally very pragmatic and duplicitous in their interactions with the Federation. Beginning with Star Trek: The Motion Picture and a visual redesign of the species (which is a contentious topic all on its own), they started drifting more and more towards a "space viking" culture. By the time of Deep Space Nine and the TNG movies, they were always seen in battle armor no matter their role, were eating like wild animals (complete with the addition of prominent canine teeth), obsessed over honor and a glorious death in battle, and were basically a total reversal of the civilized but duplicitous Original Series incarnation.
 * The makeup issues of various Rubber Forehead Aliens can be seen as this. In addition to the ridges-or-no-ridges Klingon and Romulan cases, several races underwent several adjustments on the way to their current depictions. The Trill are completely different to the point that a fan theory is that the name similarity may be coincidence, and even the Bajorans originally had little Y protrusions above their noses that they lost by the time of Deep Space Nine.
 * In Star Trek: First Contact, Zefram Cochrane is shown as the man who not only created warp drive, but also conducted the first warp flight and made first contact with an extraterrestrial species shortly afterward. In the TOS episode "Metamorphosis", where the character originated, he was said to simply be the inventor of warp drive. No more, no less.
 * Also, the Prime Directive started off as something like a principle of anthropological objectivity: How do you study a culture in its natural state? By not letting them know that you're there, obviously. It also allowed Federation scientists to avoid morally-dubious "A God Am I" scenarios. But as the series progressed, it became treated more and more as a moral philosophy, until, on Enterprise, it finally assumed a near-mystical quality with Starfleet not wanting to interfere with the "destinies" of primitive cultures.
 * In "Where No Man Has Gone Before", the second Trek pilot, Spock says that one of his ancestors married a human female. Somewhere along the line, this member of Spock's family got changed from being an ancestor to his actual father. The Maligned Mixed Marriage of Spock's parents is now an essential part of his character.
 * Doctor Who:
 * When the Daleks first appeared in Doctor Who they threatened a small tribe of people and, themselves, constituted just an isolated group in one city. In their next appearance (supposedly set earlier in history), they had successfully conquered Earth. In their third appearance they had Time Travel. In their fourth appearance, they had Time Travel and threatened Earth's entire galaxy (and probably other galaxies besides.) Along the way, the Daleks became increasingly machinelike in their speech. Destiny of the Daleks described them as literally, organic creatures which had literally become machines. (Later continuity would ignore this development.)
 * More significantly, the origin of the Daleks changed; they were originally the mutated survivors of a war, and were later shown to have been deliberately created by Davros. And both stories were written by Terry Nation, who created the Daleks. This is somewhat justified as Davros' creation of the Daleks was explained to originally been designing a travel machine for the eventual mutated form of the Kaleds as a result of the war. He then just decided to mess around with the mutants to make them think as the Daleks now do.
 * The Time Lords, the Doctor's people, established as beings who never ever ever interfered with other planets, had the Doctor doing errands for them within two years of real time. (This later got Retconned away as Time Lord covert ops missions. As well, after the Time Lords got introduced (previously the Doctor only belonged to a nameless and mysterious Human Alien species) he often ran into people and civilizations who knew of them.
 * Doctor Who continuity now runs on pure Timey-Wimey Ball, with the Time War thrown in for good measure.
 * When the mythic Time Lord Rassilon is first mentioned in The Deadly Assassin, the Doctor has apparently never heard of him. As the backstory of Rassilon evolved over the years, this became less and less believable, until it currently appears that Rassilon is not only as famous as, say, Jesus, but that the Doctor knew him personally.
 * The new Battlestar Galactica:
 * The miniseries says that after the first Cylon war, the Cylons left and made their home on a distant planet. This is brought up again in Season 2 when it is explained that the resurrection ships allow cylons to download when far from the Cylon homeworld. After that, the idea seems to have been quietly dropped. Season 4 introduces a spaceborne "resurrection hub," which is said to be essential to all Cylon resurrection everywhere, and the homeworld is never mentioned. In the last few episodes, this is brought up again, although it is changed a bit more: the Cylons had been living on the 'Colony' which was more like a large space station than a planet.
 * This trope can sort of be applied to the show's visual effects, too. At the beginning of the series—the miniseries through to Season 2 -- there was a lot of emphasis on the spacecraft behaving like spacecraft actually would, with noticeably unique—and awesome because of it—space battles in amongst the politics and drama. From Season 3 onwards, the battles got gradually more and more glitzy and dominated by the Rule of Cool. The battle of the Colony, the final battle of the series, had much more in common with the destruction of the second Death Star than the more understated and nuanced battles in the first two series.
 * Six's glowing spine that lights up during sex in the mini.
 * Season 3 of Heroes has done a lot of this, most notably in the backstory/flashback episodes "Villains" and "1961".
 * When the Genii first appeared on Stargate Atlantis, they appeared to be a Space Amish society until it was discovered they were actually far more advanced and kept it a secret by living in Elaborate Underground Bases. Teyla, who had been friends with the Genii for years, complained that they never told her and they replied "that is our way". Several episodes later, the Genii were making no effort to hide their advancements and by the fifth season it seemed to be common knowledge that they were a major power.
 * This is plausibly explained as them simply abandoning their secrecy since it had already gotten out. With the Atlantis expedition knowing the truth about them and considering them enemies (and therefore quite likely to blow their cover anyway), what would be the point of keeping up the ruse?
 * In Frasier, Hester comes off very differently in her appearance in Cheers than in her flashbacks and stories in Frasier. She threatens to kill Diane, for one thing, while on Frasier she was always touted as a bastion of class and common sense (although this could be a case of Never Speak Ill of the Dead). Also, she seems to be a rather soft-spoken, frail, grandmotherly woman who Frasier treats with great gentleness and care on Cheers, whereas she was described as a bold, intimidating matriarch on Frasier.
 * Boy Meets World: As Cory and Topanga's Romance Arc progresses, their history seems to drift also. In the early years of the show, Topanga was a Cloudcuckoolander whose crush on a very unamused Cory was Played for Laughs. Later, there are many references to them having been totally in love since they were in Pull-Ups. She is shown in an early episode giving him his first kiss though.
 * This is Handwaved later by saying that Cory and Topanga were best friends when they were really little until Cory was teased by other little boys for the friendship. As a result, he abandoned the friendship and didn't rediscover his feelings for Topanga until puberty. At one point, his big brother even takes credit (laughing about it) for convincing little Cory that girls were gross, contributing to the temporary split with Topanga.
 * Red Dwarf starts off saying that Lister never dated Kochanski, but later says that he did but that it wasn't very successful. The reason for this is that the episode where he says he did date her is based on part of the spin-off book "Infinity Welcomes Careful Drivers" which takes place in a somewhat alternate continuity. In a similar way, Kochanski is introduced in Series 7 by being from a parallel universe, which handwaves the fact that she's played by a different actress. However, flashbacks from this point on to before Series 1 have the same actress play Kochanski, which was understandable as they couldn't get the original actress, but it still doesn't make sense in continuity.

Video Games

 * In the first Ace Attorney game, the protagonist, after, says that he'd never imagined the possibility of him  . The third game has a flashback case taking place before the first game where, surprise surprise,.
 * Also, in the first game, when Phoenix and Grossberg first meet, it's implied they never met, even though he appears in that first case of the third game.
 * In the Baldur's Gate series, a great many things don't quite fit together. First comes Imoen, of whom we cannot be quite sure when we met her or why she can be revived after dying . In the Throne of Bhaal we meet a fully grown dragon of about the your age (20 years) and even with mature offspring by his side. At least what your stepfather's letter told you about your mother may be explained away as an attempt to not further upset you.
 * Except there's nothing saying that all the Bhaalspawn are the same age. After all, Bhaal's death had been foretold centuries earlier, presumably he could've started making heirs early enough for a dragon to grow up.
 * Metal Gear Solid originally began as a direct sequel to the MSX2 Metal Gear games (Metal Gear and Metal Gear 2: Solid Snake) and many of the plot points were carried over unchanged. However as the prequels were released (namely Metal Gear Solid 3: Snake Eater, Metal Gear Solid: Portable Ops and Metal Gear Solid Peace Walker) many details of the series' backstory were changed to the point that they no longer sync with the MSX games.
 * Curiously, if Naked Snake dies at any point during Metal Gear Solid 3: Snake Eater, the words "SNAKE IS DEAD" slowly change to "TIME PARADOX".
 * The Crysis series has gone through this in regards to the main alien enemies, the Ceph. In the first game, they were jellyfish-like blue critters that thrived happily in very, very low temperatures and environments with little gravity. In fact, they considered Earth inhospitable enough that you never fought them in person outside a controlled environment. Also, most of their weapons were cold-based. Come the second game and they're orange, walking around outside with the help of powered armor, no longer seem to mind the temperature, and use fusion-type weaponry and biological warfare as opposed to their original cryo-weaponry. As the aliens in the second game are very effective villains, opinion is divided as to whether or not these changes were for the better.
 * Escape from Monkey Island has Herman Toothrot be revealed as Elaine's father. This would be a genius retcon were it not for that the facts surrounding Marley's arrival on the island contradict with Herman's. This is the main reason the game has such a Broken Base.
 * Touhou: Most of the games made before Phantasmagoria of Flower View don't fit well with later canon. The first five have just been ignored. The sixth through eighth are definitely canon, but present Gensoukyou as a large place, filled with mystery and danger, while later worldbuilding would establish it as small and human deaths as rare.

Web Comics

 * The Order of the Stick: This very early OoTS comic implies that Roy's father and mother share realms in the afterlife, which they are later shown not to. Luckily, it's early enough that you can ignore it, and it's only one line (which has possible Fridge Brilliance attached).
 * In early Ozy and Millie comics, Millie lived with both her parents. Much, much later, we discover that
 * Narrowly averted in Domain Tnemrot. In a blog post, Herbert says the original 4th chapter gave a history that conflicted with the one mentioned in the About page, so he changed everything around at the last second.
 * Homestuck: In one early conversation between Karkat and Sollux, the two trolls insult each other by saying that the other is repulsive to the opposite sex, and on another occasion, Feferi immediately assumes that Eridan's crush is female, before considering that it might be male. Both of these conversations seem to imply that troll society is heteronormative; however, it is later established that the trolls are all bisexual, and don't even have a word for monosexuality.
 * This one doesn't really hold up. Feferi KNEW Eridan liked her, thus knew it was a female, and Karkat and Sollux both know each other well enough to know their respective love interests are female.

Western Animation

 * The pilot episode of Futurama stated that all jobs were selected for everyone by the government, everyone had "job chips" implanted in their hands, and leaving your job was punishable by death. Nowadays, the job chips seems to function mostly as a form of ID, with everyone taking the job they want.
 * In addition at the end of the pilot they were escaping the police and Nixon in an explosion of fireworks. This issue is never brought back up in the following episodes.
 * It should be noted that they did hang a lampshade on it in a later episode (when they are fired from Planet express and take up their old jobs again and Fry meets his ex girlfriend) by having Leela explain the concept of career chips to a dumbfounded Fry.
 * Another early episode had Bender joining a robot religion led by Preacher Bot and swearing off alcohol for the religiously acceptable synthetic oil. And yet the very first episode established that alcohol is necessary for a robot to function (there's even a legal limit that robots have to be above), and Preacher Bot is even seen handing out alcohol to homeless robots in the first Christmas Episode. This is never addressed.
 * They argue in the episode that robots are also able to use 'mineral oil' instead of alcohol. Presumably alcohol is either cheaper or easier to produce (or both).
 * Early on in Static Shock, Virgil/Static would make several references to other superheroes as fictional characters, remarking ''Even Clark Kent had a day job." Later on, however, the show is very firmly established in The DCAU. According to Word of God, "Don't worry about it."
 * In SpongeBob SquarePants, the eponymous sponge and his friend Patrick can't go into Sandy's tree-dome without a helmet full of water, but in "House Sittin' for Sandy", for some reason, he forgets that until Patrick shows up and reminds him.