Future Imperfect

""Were there eight kings of the name of Henry in England, or were there eighty? Never mind; someday it will be recorded that there was only one, and the attributes of all of them will be combined into his compressed and consensus story.""

- R. A. Lafferty, And Read the Flesh Between the Lines

People in the future tend to misunderstand past culture in funny ways. The further one goes into the future, the more distorted history seems to become. Apparently, history is the one science that gets worse rather than better in the distant future (though sometimes the fall of civilization destroyed all the data). Also, as time goes on, language shifts and evolves, while the historical data might not. In three hundred years, how many people will know what a Cotton Gin was for? How many people will actually be able to identify one? How many people will think it's booze made from distilled cotton? How many people already do?

A little strange when it appears in societies that use Time Travel, since they could always just go back and check. Occasionally inverted by a Fan of the Past.

Compare And Man Grew Proud. Often occurs in concert with Days of Future Past. See also Earth-That-Was. When done well, it tends to be a form of Entertainingly Wrong. When present-day writers get the past wrong, it's Anachronism Stew; similarly, when past writers predicted the then-future/now-past badly, that's Zeerust. Related to Famed in Story and Shrouded in Myth.

Advertising

 * A 1980s Pepsi commercial featured a far-future archaeology class visiting a recently-excavated 20th century house. The professor humorously misidentifies the purpose of several objects in the house, but when one of the Pepsi-drinking students presents him with a Coke bottle and asks what it is, the baffled professor responds "I have no idea!".

Anime and Manga

 * Tengen Toppa Gurren Lagann is set so far After the End that Kamina is considered crazy by his entire underground village for believing that humans once lived on the surface of the Earth. At the beginning of the series, some villagers are skeptical that a surface actually exists.
 * Eureka Seven has a similar situation to the Gurren Lagann example above. Humans have been living on the surface for so long, that everyone has forgotten that
 * Inverted in Cowboy Bebop. Jet and Spike consult an antique electronics dealer to identify a strange item called a "Betamax videocassette". This Fan of the Past is overcome with excitement, and proceeds to bore the two hardened bounty hunters to distraction with every arcane detail of the 1980s video format wars.

Comic Books

 * Members of DC's Legion of Super-Heroes, transported a thousand years into the past to 1990s America, mistake a fairly average wall for the Great Wall of China. A lampshading from the Post-Zero Crisis Legion of Super-Heroes. A museum curator in the 30th century tells visitors: "-and of all the surviving structures of the second millennium, we know the most about the Alamo. For example, it was here that Panamanian strongman George Washington wrote his classic poem, "The Raven"-"
 * Transmetropolitan takes place in a future where no one even knows for sure what year it is.
 * When Spider tells a presidential candidate who just quoted Tennyson's Ulysses that it was Bobby Kennedy's favorite poem, his campaign manager says, "I'm sorry, who?"
 * "Who was Hitler?" "Rock star. He was in Led Zeppelin. Fucked goats and wrote the old National Anthem. Blew up Auckland in The Blitz."
 * The concept behind many of the DC's 1996 "Legends of the Dead Earth" annuals. Whether recounting stories of 20th century superheroes, or trying to follow in their footsteps, the people of the distant future get a lot of things wrong. The Catwoman annual has Selina and Bruce as an Outlaw Couple, the Superboy one is set on a world where the legend of Superman has been merged with Aztec mythology, and the Aquaman one has two storytellers (implied to be the last survivors of Atlantis) come to blows over whether Arthur was a hero or a villain.
 * Amazing Spider-Man #439 "There Once Was A Spider..!" written by Tom DeFalco. It featured future archaeologists having discovered one of Spidey's webshooters in an old building, and intertwined with the "current" timeline. How they perceive Spider-Man ranges from the generous to the outlandish to just plain inaccurate. For example, they thought the wall-crawler was often praised (cut to a cop "today" telling him to "SCRAM!") and that his wife was the envy of her friends (cut to MJ, alone, weeping with worry). What's more, there are some nods to a certain pointy-eared hero.
 * When Bishop first traveled to the current time, he didn't believe the X-Men were who they said, because their exploits had become so legendary by his time that they were basically viewed as gods.

Fan Works
""Among the sorcerers of Zerox, Harry Potter's name is spoken in whispers," Mysa explained. "His power was unparalleled; he stopped an assassination attempt by the Dark Lord Walmart, his era's version of Mordru, when he was less than two years old. As he grew, so did his power. In his third year of education in magic, he banished an entire horde of demons; in his fourth, he bested challengers decades his senior in a contest of champions; after he left school, he faced off against the resurrected Dark Lord and his Dread Associates, aided only by the fabled Master Strategist Roonil Wazlib, and their faithful cook and quartermaster, Hermione Granger. ... [He] was a giant of a man.""
 * Legion by Clell65619 hinges on this. Faced with the villainous super-wizard Mordru's successful conquest of the galaxy, the surviving members of The Legion of Super Heroes time-travel to the late 20th century to recruit the greatest wizard known to history -- Harry Potter:

Film

 * In Woody Allen's Sleeper, future scientists question Woody Allen's character about a number of things from the 70s, and discuss their theories concerning those objects with him. Their ideas are almost entirely nonsense. Unfortunately, Woody's explanations don't help matters.
 * The in Idiocracy.
 * "1939, when Charlie Chaplin and his evil Nazi regime enslaved Europe and tried to take over the world." With dinosaurs. "And then the UN (pronounced uhn, not like the normal you-ehn) un-nazi'd the world (cue dinosaur with swastika and dinosaur with UN logo fighting).
 * Particularly ironic in that, though Chaplin looked like Adolf Hitler, he was actually called a communist after his later films.
 * A bit of Fridge Brilliance - Charlie Chaplin played a Hitler look-alike in a 1940 film The Great Dictator. This makes the Idiocracy view of history that much more understandable.
 * In the opening of Star Trek V the Final Frontier, Spock roasts "Marsh Melons" over the campfire, with some explanation of how they are traditional when camping. This was retconned in the Novelization. McCoy edited computer records of classic camping activities when he learned Spock was going with them. Spock realized the records had been altered, but played along so as not to spoil the experience.
 * The half-feral children in Mad Max Beyond Thunderdome had pieced together their own religion and historical accounts from fading memories of the parents who'd left them behind, and stray bric-a-brac of civilization. ("Remember this?" "Mrs. Walker!")
 * In Waterworld, a yo-yo, exercise machine, and flute is mistaken for garrote wire, a torture device, and spy listener.
 * In Battlefield Earth, fast-food and automobiles are the stuff of legends, and mannequins are people punished for offending the gods. The Psychlos are shown at one point examining old Earth photos of people driving with their dogs, leading them to believe that the dogs were the superior species since they had the humans chauffeuring them around.

Literature
"LETO II: Does anyone remember these names and places now? I have given you enough clues: Try to name the planet."
 * In Gathering Blue, crossing over with Shrouded in Myth - the Christian Cross is known as "The Worship Object". Because of The Ruin, all knowledge has been lost about it to the community, but the citizens, knowing that it was important in the past, worship it out of sheer respect.
 * In Peter Ackroyd's The Plato Papers, set in the far future, the titular character is a Socratic orator as well as a student and teacher history. He specializes in studying our own age, which he loves to expound on. Most of the works of the great author Charles Dickens have been lost, except one: the novel The Origin of Species brilliantly satirizes the attitudes of the time while pretending to talk about natural phenomena. Most of what they know about the past land of "America" comes from a volume Tales and Histories retrieved from a casket labeled "E. A. Poe. American. 1809-1849". They believe that the inscription stands for "Eminent American Poet", indicating that "Poet" was a title given to historians as well as the writers of verse. It was a gloomy age—corroborated by other information that people of our time were obsessed with "webs" and "nets". They also uncovered an (ancient to them, far future to us) statue of a goddess inscribed with a map of the London Underground, from a time when the city of London was worshiped as a deity (none of this gives away any plot, by the way). The book works the other way around, as well, showing how different our conception of "reality" is from what is known in this far future time.
 * In Foundation novels (after which Psychohistorical Crisis is modeled), the Empire's inhabitants don't even know what planet humans evolved on. Not only that, but there are those who scoff at the idea of humanity having come from a single planet at all, convergent evolution being the preferred model of Imperial philosophers.
 * In William R. Forstchen's Wing Commander novels, a few references indicate that they take certain movie stars to have been the people they portrayed in their films (if memory serves, they think John Wayne was actually a cowboy) although there is some confusion about why the "historical evidence" (movies) is so self-contradictory. Additionally, the Kilrathi think Bugs Bunny is some kind of important figure, and sometimes insult him in an attempt to taunt human pilots, much to the amusement of the humans.
 * In Harry Harrison's The Stainless Steel Rat series, the long-lost ancestral home of humanity is referred to as "Earth, or maybe Dirt". They're not all that convinced about the claim, either.
 * In Donald Kingsbury's novel Psychohistorical Crisis the inhabitants of the Galactic Empire thousands of years in the future have a legend stating that slavery ended on Earth when the slave Lincoln went up to Mount Sinai to receive the Magna Carta from God. They also believe the Empire invented the metric system and had to force it on Earth. Oddly, they know a considerable amount about Sumerian culture because the stone tablets they wrote on have lasted much longer than the books and discs that we recorded our information on.
 * David Macaulay's Motel of the Mysteries is the story of a group of far-future quasi-Victorian archaeologists who uncover the buried remains of a 20th-Century American motel under a hundred feet of civilization's accumulated trash and decide that it's a sacred burial site. In a parody of contemporary archeological discoveries, the toilet is considered to be the holy of holies, given its place of honor.
 * The Sirens of Titan features a man who claims to have the ability to see the future, who then predicts that in the year 10 million, all historical events from the year 0 A.D. to 1 million A.D. will be forgotten. Instead, history textbooks will read (paraphrased): Following the birth of Jesus Christ, there was a period of readjustment that lasted approximately one million years.
 * In Eternity Road by Jack McDevitt, a future civilization studies the religious monuments of the past. Highways. They must have been of great spiritual significance, because the ancestors built them everywhere. They even call our civilization the "Roadmakers".
 * A Canticle for Leibowitz has a fair number of these, such as the shopping list treated as a holy relic (in fairness, it was written by the martyred St. Leibowitz the Engineer, so it actually was a relic even though it was a shopping list), the difficulties a novice (i.e., member of a monastic novitiate) has in figuring out what "Fallout Survival Shelter" means, the barbarian nomads who swallow electrical resistors to commune with spirits, and the Renaissance scholar who reads R.U.R. and takes it a little too much to heart...
 * Robert Nathan's The Weans has future anthropologists give the titular name to the (now lost) American civilization, because all their most important artefacts are stamped with the word "US". Accounts of the Nacirema tribe are in a similar vein.
 * Harry Potter doesn't exactly have this in the future, so to speak, but the way the wizards address Muggle inventions is the same. Conversely, several offhand comments throughout the books suggest that Muggle history is wildly wrong, as the Ministry and its predecessors have been modifying memories to maintain The Masquerade for centuries.
 * Played for Drama in 1984 by George Orwell, where historical records are actually altered by the ministry of truth to make the Party look good. They say they invented the airplane, for one thing. The protagonists still remembers the time when they only claimed to have invented the helicopter... and predicts they'll soon be saying they invented the steam engine.
 * Will Self's The Book of Dave, in which the diary of a bitter current-day London cab driver becomes the holy book of a religion 500 years in the future. As he was divorced, the "Mummies" and "Daddies" live in separate housing, and their children switch between them.
 * A timeline of the history of the galaxy presented in The Dune Encyclopedia, a companion text to the book series by Frank Herbert, provides a distorted description of Earth history as seen from the perspective of that era. The "Galactic Empire" is described as being founded by Alexander the Great, its capital moving several hundred years later to Madrid, then London, then to Washington as the result of a civil war. The "House of Washington" was the first to use "stone burners", i.e. atomic weapons.
 * Stilgar in Dune Messiah did not understand why "Emperor" Hitler was considered so historically significant, having killed "only" a few dozen millions of people.
 * Which is weird, considering how many characters in the series have access to the memories of their ancestors and predecessors (in Duniverse terms, "Other Memory"). As Emperor Leto II writes in his journals after discussing an ancestor's conquests in ancient Israel and Babylon:

""URIAH S. (or Z.) GRAUNT--popular poet of ancient times in the Aztec provinces of the United States of British America. Some authors say flourished about A. D. 742; but the learned Ah-ah Foo-foo states that he was a contemporary of Scharkspyre, the English poet, and flourished about A. D. 1328, some three centuries after the Trojan war instead of before it. He wrote 'Rock me to Sleep, Mother.'""
 * "House of Steel", which was eventually defeated when the House of Washington managed to outproduce it industrially. Sounds like an odd name for the USSR, until you realize that "Man of Steel" was the translation of the name for its most infamous ruler, Josef Vissarionovich Djugashvili. You may know him better as Josef Stalin.
 * In The Tenth Planet, set 5,000 years in the future, one character recites "The legend of the Jesus Freak", a garbled and mish-mashed version of Christian beliefs, which included, among other things, "The Jesus Freak" resurrecting by giving himself a brain transplant.
 * A twisted version in Henry Hazlitt's Time Will Run Back (revised edition of THE GREAT IDEA). In the global Communist dictatorship of Wonworld (sic), ritualized denunciations of "capitalism" continue, but the records of the past have been so thoroughly censored that nobody remembers just what capitalism actually was or how it worked. Here it is deliberate policy by the dictatorship, which has expurgated even the works of Marx and Lenin as insurance that nobody will be able to use them to reconstruct capitalism. So when the hero hits on the great insight—PRIVATE OWNERSHIP of the means of production—he has no idea that this is the dread capitalism.
 * Mortal Engines. Plastic statues of Mickey and Pluto, "animal-headed gods of lost America."
 * The present time of the Wheel of Time series has apparently muddled up what little they remember of past ages. In one book Thom talks with Elayne about this trope, providing in story examples of likely false history and states that for all they know he could be remembered as the Chosen One instead of Rand, and be a fireball-throwing wizard. His last name is Merrilin, however, the series is not historical fantasy, and the world of Wheel of Time is not linked to ours, a common misconception due to Jordan's appropriation of Earth's mythology.
 * Actually, the Age before the Age of Legends (which itself precedes the Age the books take place in) is almost certainly our world, with a number of references to, for starters, the Cold War, Americans landing on the moon, and at one point, the Mercedes-Benz logo, which is said to give off an air of wealth. However, these references are far from explicit, and are pretty difficult to catch. Considering the thousands of years that have passed in-universe, it's not hard to miss the reference in the first book to "Lenn and his daughter Salya, who flew to the moon in the belly of an eagle made of fire," which allude to John Glenn, Sally Ride, and the phrase "The eagle has landed."
 * It's right there in the title of the series: Time is a wheel. The events in the books are both in our future and the inspiration for the legends of our past. In the context of the series, time is cyclical, and the current events are "an age yet to come, an age long past", as the opening paragraph of every book tells us. So, both the past and the future are "our world", or a world much like our world.
 * The Anvilicious political work Ali Dubyiah and the Forty Thieves is a "historical fable" from perhaps a thousand years in the future, describing a certain early 21st-century American president and how his actions led to the fall of his empire and ultimately The End of the World as We Know It. Major players are referred to with garbled names such as "Dick Chaingang", "Condi Pasta", and "Osama bin Hiden".
 * Void Dogs has its share of Future Imperfect gags, such as the claim that The Adventures Of Tom Sawyer "?twas first told by an Irishman, as called himself MacTwain."
 * ... who (Mark Twain) actually uses this trope himself, in The Innocents Abroad, where he speculates what will become of President Grant "in the Encyclopedia for A. D. 5868, possibly":

"You just don’t know what you’re talking about! I don’t know if you’re really thick or trying to catch me out or something, but you’re talking serious bollocks. Winston Churchill was the British Prime Minister during most of the war, and when he said “we shall fight on the beaches” he was talking about how if the Nazis invaded we’d never surrender, not running on about a scrap over the buckets and spades. I lived through that, you know, and it wasn’t very nice[...] That man –’ he pointed at another of the many Elvis posters – ‘had blue suede shoes, not green rubber wellies or whatever stupid thing you’ve got him down for. And he was a singer – a fantastic one – not a teddy bear or a hotelkeeper or a hound dog. And I don’t know who killed Roger Ackroyd [...] because it wasn’t real: it was a book[...] And I don’t know what weird version of twentieth-century England you’re talking about, but I reckon it’s some stupid fake you’ve come up with after getting a few details off the back of cigarette cards and chocolate-bar wrappers and scraps from a local library, and then filling in the gaps to suit yourself."
 * In Michael Moorcock's Runestaff novels, "Granbretan's" leading playwright has chronicled memories World War II in his works "Chirshil and Adulf" and "King Staleen" ("King and court alike corrupt...") Later, we are told that the gods of the Dark Empire of Granbretan include the quartet of Jhone, Jhorg, Phowl and Rungah, and the great "Aral-Vilsn" and his sons Skveeze and Blansacredid, "the ancient words for doom and chaos". Possibly these are Anvilicious politico-economic sniping.
 * In the tie-in novel to the canceled game Starcraft: Ghost, Nova is noted to have learned that it was the Germans who performed the Kamikaze attacks back in WWII. Justified in that she lives on a Lost Colony and the ships that brought them there had faulty data banks. Furthermore, the colonists also took King Kong too literally, leading to the belief that giant apes exist on Earth.
 * In Charles Stross' Glasshouse the setting and catalyst for the plot is an experimental society based on the era before the Acceleration the knowledge of which is lost, having been stored on fragile and/or incompatible media. The idea being to use what is known to make a convincing simulation and study the interactions of its residents to fill in the rest. Naturally, there are obvious (to us today) inconsistencies.
 * In Stross's Iron Sunrise Rachel Mansour reflects on the 20th century: "a time populated by women in bonnets and ballooning skirts, men in backward baseball caps and plus-fours, zeppelins and jumbos circling overhead".
 * Not set in the future, but similar: in Rutherford's Sarum, a medieval scholar teaches his student that England had two great kings in centuries past. One was King Arthur, and the other was Old King Cole. Could be Truth in Television, depending on how feeble the state of knowledge actually was at the time. There is a theory that the nursery rhyme "Old King Cole" does commemorate a real king, probably a celtic leader called Coel, sometimes identified as Emperor Constantine the Great's father-in-law. So it's not quite as mad as it sounds...
 * Harry Turtledove combined this trope with Crippling Overspecialization in "The Barbecue, the Movie, & Other Unfortunately Not So Relevant Material". In this short story, a time traveling historian from thousands of years in the future is intimately familiar with the life and times of Genghis Khan, but when he is accidentally transported to the twentieth century, he mistakes the cars outside for cows.
 * A somewhat milder version is used in Honor Harrington, where different planets retained different things in the transition from Earth to the "present" of the books. For example, Honor, while on Grayson, spots a large group of men walking through a park with wooden clubs and immediately assumes they are an angry mob (There has been much political and social tension of late, and an outbreak of mob violence is unpleasantly likely). She is about to call in her police forces when Andrew LaFollet points out they are just playing baseball, and those are just bats, not clubs. She has never heard of baseball, and asks if it is at all like golf, which Andrew has never heard of, and they spend a few minutes going back and forth, each comparing one sport to a different sport that the other has never heard of. In another book, William Alexander is visiting Grayson and remarks on how novel Iced Tea is, and how he is looking forward to introduce it at his next dinner party back on Manticore, while his older brother (Hamish Alexander) is impressed with the buttery-goodness of waffles, which he thinks compare quite favorably with the pancakes of Manticore. However, there is some information that has been lost to both cultures, as it seems that nobody can figure out just what a "movie" is, even though they know for a fact that at least one copy of Seven Samurai was brought on the original colony ship to Grayson.
 * Alien Landscapes, a collection of art based on various SF stories, has as its premise that all said stories take places in the same universe. It contains a "future newspaper", one of whose articles describes a museum in a manner lampshading this trope. "A boot from... the planet Poland (location no longer known)", a primitive tracked vehicle called a "voleswakan", and "stylized phalluses... called Bishopricks... used in early risque versions of... chess" are listed among the exhibits.
 * Starship Troopers (the novel, not the movie):
 * Ramon Magsaysay is identified as, amongst others, having married Cleopatra.
 * There's also a joke in the Mobile Infantry where a Trooper visits Napoleon's grave and asks the guard who that is. The guard tells the trooper that Napoleon is the greatest soldier who ever lived, prompting the trooper to ask him where his drops were.
 * Justified in both cases by the protagonist 1) pulling the leg of a non-Filipino squadmate and 2) showing signs of being a Snark Knight.
 * Edgar Allan Poe helps make this one Older Than Radio, and is sometimes credited as the first modern, sci-fi use of this trope, in the short story "Mellonta Tauta", presented as a journal from the year 2848. The journal's writer details her conversations with a historian and her world's concept of ancient history, based on wildly inaccurate and overly literal interpretations of present day records: among other things, they think silk was made from earthworms that ate mulberries, that a Turkish philosopher named Aries Tottle invented science, and that America was founded by warring tribes of cannibals.
 * In Michael Moorcock's Dancers At The End Of Time this trope is rife. Although, they are at the end of time, so perhaps a little memory slippage and creative license is allowed.
 * There is a book by Kir Bulychev about a planet which suffered a collective Memory Wipe a couple of centuries ago. As a result: 1) The people there are mixing up words - some nobles call themselves "Moles" thinking it means "Wolves", and the king calls himself "Radiculitis" thinking it's "Elephant". 2) Said king uses an ancient dentist's chair for a throne, and his bodyguards use chamberpots for helms. 3) Forgetfulness is a religion. 4) A small society exists of outlaws who actually try to reconstruct the past - and while they are quite accurate, it takes a traveler from another planet to explain them what this device is for.
 * Deliberately invoked in Michael Resnick's future history novels where characters in (chronologically) later novels often display mistaken/imperfect/misbegotten ideas about "historical" events that took place in earlier books.
 * Cordwainer Smith's Instrumentality stories often contain throwaway references to knowledge that filtered down imperfectly from our times. The Instrumentality is headquartered, for instance, in a Terran city called Meeya Meefla—so called because nobody can remember what the original pronunciation of 'MIAMI FLA.' was.
 * In The Book of the New Sun the protagonist carries around a book of the ancient legends of Earth Urth. One of them is a mashup of the story of Romulus with the story of Mowgli (because they were both raised by wolves) and another has the story of Theseus and the Minotaur mixed up with the real-life Battle of Hampton Roads (where one of the ships was called the Monitor).
 * Similar to the page quote, in the Island in The Sea of Time trilogy by S.M. Stirling, an academically-trained character shocks the others by informing them that within fifty or a hundred years, no-one will believe that the island really came back through time, no matter how well records are preserved: everyone will be scrambling to figure out theories that "prove" 20th century Nantucket developed by itself in the Bronze Age.
 * In universe example: there's a thousand-year time gap between the Obsidian Mountain trilogy and its sequel. The characters from the first are treated with religious veneration in the second, and almost all the details are mixed up.
 * In the Uglies series, schools do not necessarily teach children the exact truth of human history.
 * Third Earth (Earth in the early 51st Century AD) in The Pendragon Adventure inverts this. As one character put it, they "know everything about everyone and everything they ever did."
 * Hyperion does this very subtly. The Leader of the Earth Hegemony frequently steals her best lines from speeches made by Winston Churchill, and this is Lampshaded more than once. However, the one time Hitler is mentioned, the listener doesn't recognize the name, and he's then described as "An Earth-politician who sold a lot of books no one actually read."
 * Return From the Stars has the protagonist attend a theatre play in the 127-year future, set in what is roughly present day. He comments that they got the customs and clothing of that period wrong. Note that, due to a huge overhaul in human psychology (a forceful treatment that removes all aggressive impulses instilled in every man's early childhood), the "old times" but a hundred years ago are even more incomprehensible for the future Earth-folk than Medieval times are for us.
 * The Flowered Thundermug is a story about a future where the entire world was rebuilt from the only area left intact after a nuclear war - Hollywood.
 * In Battlefield Earth the story of Earth's invasion and occupation by the Psychlos is remembered as a religious purge of the planet by 'the gods.' Their legends speak of a deadly cloud that swept over the land (The initial barrage of poison gas) and then a wave of monsters and demons that hounded and pursued the survivors from the cloud (The arrival of the Psychlos themselves, who exterminated whatever humans they could find). This was all done by the gods in order to remove the sinful and impure from the planet, and their ancestors survived because they honored the gods and were righteous (They lived in the shadow of a massive military complex that served as a government retreat and survival bunker, surrounded by last-ditch nuclear explosives whose radiation kept the Psychlos away). When Jonnie Goodboy Tyler, the protagonist, encounters other isolated people, they each have their own legend of what happened. The Scots, who have managed to retain a semi-accurate history because their territory received less attention from the Psychlos, remember America as a distant village that some other Scots went to and settled a long time ago.
 * Stephen Vincent Benet's short story "By the Waters of Babylon" supposes that not only has the United States of America ceased to exist as we remember it (apparently, it was destroyed in a great war), but the descendants of modern-day Americans have returned to living in tribes, hunting wild game with bows and arrows and forsaking Christianity for polytheism (believing, for example, that their ancient ancestors were actually gods). The protagonist finds a torn-up dollar bill at one of the ancient ruins and notes that it features an image of a man with long hair like a woman - in other words, George Washington. However, the protagonist can only call Washington "Ashing," as only that much of the inscription on the bill is left intact. He assumes that "Ashing" is a god, and offers a brief prayer to him out of respect.
 * Averted in Timeline, where the resident Medievalist does get some things wrong when they travel back in time, but is also right on nearly everything else and is virtually able to pass as a local.
 * Justified in the Warhammer 40k "Horus Heresy" novel, Prospero Burns. The protagonist notes that this is happening at an alarming rate all over the young Imperium, due to the cataclysmic event of Old Night (and the increasing dominance of monolithic beaurocracy. The organization he set up is intended to counter this very trope. It isn't working too well; another character mentions that it must be working because they have managed to recover copies of all three of Shackspire's plays.
 * The Doctor Who Eighth Doctor Adventures novel EarthWorld features this heavily. Fitz is quizzed on 20th-century history from someone in the far future, featuring questions such as, "Which English politician was well-known for his seaside boxing matches?" and decides to set the record straight:

"'As with Slaydo, the places where the heroes fell. Captain Menhort of the Kolstec "Hammers", and, of course, Alltenis.' 'What?' asked Gaunt. 'Did you say  ?' asked Jaume. ' ,' said the docent. 'He died taking down the Tower.' Gaunt looked back at his companions. ' ' he whispered."
 * In the Doctor Who Virgin New Adventures books, Ace (the companion from the eighties) steals Bernice's (archaeologist from the future, specializing in the late 20th century) notebook and spends the day laughing herself silly.
 * In the Doctor Who New Series Adventures novel The Coming of the Terraphiles by Michael Moorcock, the Terraphiles are Old Earth enthusiasts who base their understanding of Old Earth entirely on a selection of 1930s British "Boy's Own" adventure novels. Their Renaissance Festival is based around a game called Whackit, which combines cricket with archery (one of the books was The Adventures of Robin Hood).
 * Done In-Universe in the Gaunts Ghosts novel Blood Pact. The historians at Balhaut think that

"'No one remembers anything properly. Everything gets twisted and forgotten.'"
 * Later...


 * The sequel series to the Obsidian Trilogy by Mercedes Lackey has folk tales about the characters in the first trilogy that are so blatantly inaccurate (Or in some cases, just plain made up) that one has to wonder if the historians of Kellen's time period even tried to write down what was going on. Made more blatant that usual, despite the centuries long time skip between the trilogies, by the fact that due to the longevity of elves, several of the people in those stories were still alive (And for some reason had made no attempt to correct the histories).

Live Action TV
"Rain Robinson: The UFO, what is it? Tom Paris: It's a Soviet spy satellite. Part of a massive KGB operation. We're trying to stop it. Rain Robinson: Soviet? The USSR broke up five years ago. The KGB doesn't even exist anymore. Tom Paris: That's what they'd like you to think."
 * The Australian sketch comedy series 'The Comedy Company' featured a parody of David Attenborough who used this trope (played for humour of course) when examining modern society.
 * A few examples in Doctor Who
 * In The Mysterious Planet, the Three Books of Knowledge are The Water Babies, a British children's book; Moby Dick; and a UK public information volume about geese.
 * In "The End of the World", Cassandra confuses a dragon and an ostrich and misidentifies a jukebox as an iPod. She has an excuse, though... "The End of the World" is set in the year five billion. It seems at first to make her look like an idiot, though depending on how well history has been maintained, she might've done well to hit the right century.
 * This is what first draws Barbara's attention to "The Unearthly Child" Susan in the first episode, the fact that she keeps disagreeing with her version of history while messing up contemporary facts. At one point we see her looking through a history textbook and exclaiming: "But that's all wrong!"
 * In Red Dwarf:
 * Holly identifies Plato as the inventor of the plate, while Rimmer thinks that Columbo discovered America and calls Marilyn Monroe "Mary Magdalene". However, this might be because Holly's computer-senile and Rimmer is an idiot, rather than because it's the future.
 * There is a cat race that evolved from Lister's pet cat over some 3 million years. They based their culture and religious beliefs on such oddities as Lister's laundry list (which they believed to be a star map). Also, based on Lister's plan to go to Fiji, they look forward to when Cloister the Stupid will return and bring them all to the promised land, Fuschal.
 * In one episode, Lister confuses René Descartes with Popeye and manages to confuse Kryten as well. This is definitely a case of stupidity, though, as Rimmer knows the difference between the two.
 * In the episode Tikka To Ride, they find themselves in Dallas in 1963. Lister asks if this is the place where "that American king was assassinated - what was his name?" Rimmer: "JFK." Lister: "No, it was John something - not Jeff Kay!"
 * In Space: Above and Beyond, a group of recruits on a training expedition on Mars come across a 1970s NASA probe which, when jostled begins playing the song "Blitzkrieg Bop", by the Ramones. One of the recruits, a self-proclaimed 20th-century rock aficionado, misidentifies it as being by "The Pink Floyd".
 * A standing joke in the Buck Rogers TV series, in which a bemused Buck was constantly having to explain to eminent archeologists that a recently unearthed 20th century hair dryer isn't a prototype hand laser, or some such.
 * Babylon 5:
 * Episode "The Deconstruction of Falling Stars" illustrates the far-reaching consequences of the Interstellar Alliance's actions. One hundred years in the future, there's a revisionist movement to clear President Clark's name, and Sheridan's actions are severely downplayed at best. Fortunately, Delenn's still alive to smack some sense into everyone.
 * Another four hundred years later, Delenn is also dead and the results are accordant.
 * Star Trek: Oddly enough, one of the most perfect futures of all seems to fall into this trope at times. Characters often display a glaring degree of ignorance as to the workings of 20th century (or prior) Earth.
 * This is particularly notable in the episode of Star Trek: The Next Generation that introduces the Holodeck, where even the ship's resident Red Shirt Historian is shown to be fairly clueless about how a 1930s era American city works.
 * Made even worse by the fact that Kirk and Spock had at least outline knowledge of 1920's Chicago in the TOS episode A Piece of the Action (with Spock specifically mentioning the effects of gang warfare on 20th-century Chicago's infrastructure) and a book on Chicago gangsters of the era was in print at most a hundred years prior to that episode. Kirk, Spock, and McCoy also seem to have a decent working knowledge of the era in The City on the Edge of Forever (along with access to an artifact that could clarify any discrepancies just by asking). Was the knowledge somehow lost in the century between Kirk and Picard?
 * In First Contact, which unusually does this to events that are in the past from the perspective of the crew, but our future (the 2060s). This crosses over with Shrouded in Myth, as it turns out that the much-idolized architect of warp drive, Zefram Cochrane, built the drive purely to make money, rather than out of some higher dreams or ideals (though of course, given the post-apocalyptic Crapsack World he lived in, he could be forgiven—and Cochrane himself had more trouble accepting the dissonance between who he really was and how the future would remember him, than did Enterprise's crew). Of course, he eventually became one of the key figures in humanity's getting itself back together, presumably influenced by the effects of first contact.
 * Star Trek: Deep Space Nine presents an episode where Sisko has the senior staff play baseball on the holosuite. O'Brien decides to get into the spirit of things and researches the concept, only to find a traditional snack that had since passed into antiquity: chewing gum. Of course, he flavored it with Scotch. Thus successfully combining two classic baseball traditions: chewing gum, and getting blitzed out of your head either during the game, or immediately after your team wins or loses.
 * In another episode, a late nineties astronomer picks up a time-traveling Voyager on her instruments and sends a greeting to the aliens she assumes are on board. Tom Paris, who treats twentieth-century culture as a hobby, is sent to smooth the situation over. He tells her that he and his colleague are secret agents, and then:

"Spock: The computer isn't sure, but it thinks this "NBC" used to manufacture cookies."
 * In another Voyager example, a copy of the Doctor is activated in the distant future by an alien society that had a conflict with Voyager as it passed nearby ages earlier. In a mix of this trope and Politically-Correct History, the aliens interpreted fragmented records of the time so as to vilify Voyager's crew, imagining them as a band of bloodthirsty pirates and describing Voyager as a heavily-armed warship—because this let them interpret their own history more favourably. It is up to the Doctor to dig up historical evidence and clear the names of his long-dead crew-mates.
 * The TNG episode titled "Future Imperfect" ironically doesn't display this trope.
 * In Come Back Mrs Noah, even though it's only Twenty Minutes Into the Future, Ringo Starr is mis-identified as the inventor of the telephone.
 * In an episode of Sliders, the gang lands on an Earth that has undergone "some kind of time warp" (they don't explain it any better than that) and find 1920s-style archeologists excavating modern-day sites. One of them finds an ordinary beer mug and believes it to be a ceremonial chalice, another is mystified at the sight of a parking meter.
 * The possible tendency toward assuming something is religious in nature is referenced and lampshaded in an early episode of Stargate SG-1. Upon finding a village that is empty, with food still hot on the cooker, archaeologist Daniel Jackson mentions he thinks they might have left for a religious ceremony. Jack O'Neill goes, "Why is it always about religion with you? Maybe they just went to a swap meet"
 * There's a That Mitchell and Webb Look sketch about an After the End quiz show devoted to trying to interpret the few remaining shreds of human culture. Questions include "What was water?" and "What is the name of this pre-event leader?" while displaying a picture of comedian Eric Morecambe. Prizes include 'fuel' and a traffic cone, named as 'we don't know, but they're everywhere'. Strangely, it is mentioned twice that "the Event" happened only about two and a half years prior. Of course it's also mentioned that many people were blinded by the event, everyone takes regular medications, and sex is now very difficult because of all the vomiting. The Event messed people up in a lot of different ways.
 * In a 1970s Saturday Night Live sketch spoofing Star Trek, the Starship Enterprise is chased down by a car containing executives coming to cancel the show. Spock, played by Chevy Chase, runs a search on the license plate and finds out the car was owned by a corporation known as "NBC":

Tabletop Games

 * In the BattleTech universe due to a major loss of information and technology in general over the centuries, many people see the era of the Star League as a golden age of humanity, whereas in reality it was (for the Periphery, at least) a time of bloody crackdowns on colony rebellions and bossing around of smaller states.
 * Cyberpunk 203X takes places after a worldwide data crash in which historical documents were fragmented or plain lost, letting younger people to believe "Richard Nixon, instead of resigning over Watergate, committed suicide on camera and that memes such as the moon landing being hoaxed become prevalent", among other things.
 * The role-playing game Paranoia, which takes place After the End in a dystopian domed city ruled by a paranoid supercomputer, features a secret society called "The Romantics", whose view of human history is a mish-mash of mixed-up bits from actual history and pop culture (for example, they believe Gandalf built Stonehenge). Also, the Communist secret society, who, through their mishmashed view of history, are convinced that Communism consists of Yakov Smirnoff jokes, bad Russian accents, pictures of Groucho Marx, and the music of John Lennon.
 * Diana: Warrior Princess and Elvis: The Legendary Tours. Each game is supposedly an RPG based on a popular adventure drama set in the 20th Century, which had all the historical accuracy that Xena: Warrior Princess and Hercules: The Legendary Journeys display towards Greek antiquity, while the RPG has about the same relation to the modern reality that Dungeons & Dragons has to medieval Europe.
 * Warhammer 40,000:
 * Some in the Imperium know about the "Old Age of Earth", but their information is sketchy. Cities such as Atlantys and Nova Yourk are cited as being the most legendary and ancient cities of Old Earth. Nations known as Jermani, Merica, Britania and Bania are said by scholars to have prospered and wilted during this time.
 * Given that they have only very general records of the founding of the Imperium in the 31st millennium, it's fairly impressive that they even know Earth is the original human homeworld. Virtually everything between those tidbits and the rise of the Empire is entirely lost.
 * They do retain some basic information concerning one of the ends of the world - "Yndonesia" was a major player in one of the wars, that warriors clad in "thunder armor" were involved, and a few other details.
 * Presumably this wasn't a huge issue, since the Emperor could have easily corrected the errors, having been personally involved in many important historical events.
 * The Horus Heresy novels are rife with these. For example, a character reminisces his family's home in Merica, atop a cliff that had the carved faces of ancient kings chiselled into it.

Theater
"Adams: It doesn't matter. I won't be in the history books anyway, only you. Franklin did this and Franklin did that and Franklin did some other damn thing. Franklin smote the ground and out sprang George Washington, fully grown and on his horse. Franklin then electrified him with his miraculous lightning rod and the three of them--Franklin, Washington, and the horse-- conducted the entire revolution by themselves. Franklin: I like it."
 * In the musical 1776, John Adams complains of this:
 * beat*


 * Adams's dialogue is only slightly paraphrased from something he wrote in a letter in real life.

Video Games

 * Superhero League of Hoboken is set an unspecified length of time after "The Great Collapse", and thus things have gotten... strange. For one, George Washington and Johnny Appleseed have gotten conflated, and there's a cult based on Wheel of Fortune.
 * Despite surviving a fourth world war, the humans from the game Machines are... absent, considering the machines started terraforming over a thousand years ago and they haven't been heard of since they could all be dead.
 * The Legend of Zelda: The Wind Waker has a legend of treasures at the bottom of the sea called the "Triumph Forks",.
 * Depending on who you ask, the Zelda series as a whole may often display this through coincidental facts dropped in the backstory or something a character might say that suspiciously resembles something that happened in a past (or even future) game. For example, the introduction to The Legend of Zelda: A Link to the Past talks about seven wise sages (and shows an image of seven men) who trapped Ganon in the golden realm. When you play the prequel, The Legend of Zelda: Ocarina of Time, you discover that some of the sages weren't even human, let alone male. In addition, the figure of Ganon is often shown as a giant monster capable of consuming whole cities in the lore and myths of the present-day Hyrulians, instead of the human he actually was. (Granted he has transformed himself into a beast a few times, but never one 10 times bigger than his original form)
 * In Fallout 3, you meet a caretaker of an American History museum in Rivet City who has made quite a few mistakes, even with the history that occurred before our timelines diverged. This is justified in-universe by the nuclear war, the fact that the best sources of info in the Capital Wasteland are currently overrun with Super Mutants, the Brotherhood or both, and because other groups like the Slavers are actively attempting to destroy historical artifacts for their own ends.
 * In Fallout: New Vegas, you'll come across an Elvis-themed gang called The Kings. The Kings actually have absolutely no idea who Elvis really is: when they first discovered The School of Impersonation filled with holotapes, jackets, and a seemingly unlimited supply of hair gel, they concluded that the building was a temple of worship dedicated to some sort of a mystical god (of coolness) and decided to keep his memory alive. In fact, they don't even know Elvis' name since the non-destroyed material they found referred to him only as "The King".
 * There's also a sidequest in New Vegas where you have to collect fifty bottlecaps with stars on them rumored by several people around the wasteland to unlock some sort of great treasure. Said "treasure" turns out to be
 * Spaceout Combreak Vadermand. The concept behind the game: A group of archaeologists in the distant future attempt to create a "scientifically-accurate reconstruction of one of the very first forms of electronic entertainment." They mistake fragmented records describing three separate games (Space Invaders, Breakout, and Missile Command) for descriptions of one game. Spaceout Combreak is the result of their efforts. It's surprisingly playable.
 * As the Literature section mentioned, this trope pops up occasionally in the background material for StarCraft. Other than the examples with World War II and King Kong, this trope is also the reason why the Terran Confederacy used the "Rebel Flag" as their symbol.
 * In one Infinite Space cutscene, Gen shares "iced tea" with Yuri, saying he got the recipe from a fragment of a very old book. The drink is steaming hot and Gen admits the recipe might be missing a step.
 * Due to the fact that their progenitors erased all mention of Earth from their histories, the Argon of X: Beyond the Frontier believed Earth a myth whose only propagators were the wacky but harmless Goner fringe sect. They believed this right up to the part where a Terran test pilot named Kyle Brennan got himself marooned in the X-Universe due to the experimental jumpdrive on his ship going haywire.

Webcomics
""If the future did a documentary of the last fifty years, this is how badly their reenactors would dress.""
 * Starslip Crisis features a 35th-century holodrama called The Concrete Universe, a CSI-esque Police Procedural set in 2002. Nearly every detail is anachronistic, with the main characters traveling around in covered wagons and using fingerprint rays and scimitars.
 * This Perry Bible Fellowship shows how the future might interpret World War II in true Hollywood fashion, although it is perhaps a little exaggerated.
 * The time travelers in these two Dresden Codak strips.


 * Inverted in other Dresden Codak strips, with the Historical Preenactment Society. Yes, they recreate (if that's the right word) historical events that haven't happened yet, such as robot uprisings. How their accuracy compares to that of more mundane historical reenactment societies is left as an exercise for the reader.
 * In My Name Is Might Have Been, most of the Future Imperfect is about classic rock. There is a debate about whether Mick Jagger was a man or a woman, for one.
 * xkcd gives us the [//xkcd.com/239/ blagofaire], the future's Renaissance Faire, as well as the look at [//xkcd.com/771/ possible troubles] with Queen's English during play re-enactments. Forsooth!
 * Also, mocking [//xkcd.com/1255/ the present version].
 * And then [//xkcd.com/1259/ getting existential] (see also Alt Text).
 * Homestuck: That does not look like Rose Lalonde...
 * Freefall comic takes the idea to its logical extreme here with Florence freaking out at the sight of a sparkly Hitler doll.
 * Pain Train has this reconstruction of the opera classics.
 * Schlock Mercenary has many examples, that pop up pretty much every time pre-internet history is mentioned by anyone who didn't actually study it. Liz as a humanitarian student did study old culture, Kathryn (and presumably the rest of her team) seems to have studied military history, with anyone else… all bets are off.
 * They [//www.schlockmercenary.com/2016-06-20 remember] idiom "nuke it from orbit".
 * Trevor [//www.schlockmercenary.com/2017-01-23 knows] "Rosencrantz and Guildenstern are Hobbits" is a later crossover, but thinks Shakespeare and Tolkien knew each other.
 * Liz [//www.schlockmercenary.com/2017-03-31 mixed up] her Bradburies. Then again, she remembers them at all.

Web Original
"Fatebane: Fixed fortifications are a monument to the stupidity of man. Admiral Patton punched right through the Western Wall and sank the Japanese fleet. And that was in the days of triremes? oar-powered ships that couldn't fire back as well as coastal fortresses. Nazar: And how many ships did he lose in that battle? Fatebane: It's the principle that matters! If she could do it, so can we!"
 * In Pokegirls, there is a general lack of information about a lot of things pre-1990 (which is when The End of the World as We Know It almost happened). In addition, Sukebe is believed by a majority of people to have been an actual wizard as compared to "just" a Mad Scientist with Magitek.
 * Associated Space has the following exchange as two characters are debating strategy before an upcoming space battle:


 * Was the legendary hero Chuck Norris a real person, whose actual actions became exaggerated and mixed up with tall tales over time? See the debate here.
 * Cracked.com has "A History Channel documentary on the Beatles from the year 3000," viewable here.
 * Among other things, it attributes many songs to them, such as "Jimmy Crack Corn," "Don't Stop Believing," and "Battle Hymn of the Republic." It says they invented the concept of a song less than 3 hours long, and Scottie Pippen was the fourth Beatle, instead of Ringo.
 * Their best album is "Sgt. Pet Sounds and the Spiders from Aja, they invented the "thumbs up" gesture and Mickey Mouse, and were the stars of I Love Lucy.
 * Also the article 25 Common Items that Will Baffle Future Archeologists And its kinda-sequel, 23 Modern Images as Misunderstood by Future Archeologists.
 * In Pay Me, Bug!, most of the people who were born and raised on Earth like to claim that it's the original homeworld of humanity, but nobody else takes them seriously.
 * In Cracked.com's Photoplasty contest 26 Dramatic Movies They'll Make About Modern History, the "Anonymous" and "Riot Cop Superstar" entries and a couple others appear to imply this.

Western Animation

 * The Maximals and Predacons in Beast Wars Transformers have a sort of mythical misconception about the Great War, especially how it got started. Partly justified in that the Maximal government has done a thorough cover-up and control of all info relating to Earth, where the bulk of the Great War was fought (for some odd reason)...but then Fridge Logic smacks you in the face with the fact that several of the original Transformers (including the rebuilt Ravage) are still around and would know a great deal about what really happened.
 * Futurama seemed to have this problem too. Among other things, they mistook Ralph Kramden of The Honeymooners for a space pioneer because of his Catch Phrase "Bang! Zoom! Straight to the moon!" (as said on Futurama; see Beam Me Up, Scotty), thought there were "Whalers On The Moon" ("They Carry A Harpoon"), and credited Gerald Ford with inventing the automobile automocar. The Past-o-Rama theme park (supposedly based on the year 2000) in "The Lesser of Two Evils" is probably the best example; in a commercial, cowboys with surfer accents and hover-mopeds hunt mammoths with harpoons, and Albert Einstein and Hammurabi (who ruled Babylonia c. 2000 BCE) are seen disco dancing in a hot air balloon, and Hammurabi uses the catch phrase "Dy-no-mite!" from Good Times. Fry, who is actually from the past, is either not believed when he tries to correct the errors, or just makes them worse with his unique perspective (What were those booths on the road used for in your time? Bathrooms).
 * Roswell That Ends Well: The Professor in a 1947 diner orders "a croque monsieur, the paella, two mutton pills and a stein of mead!"
 * That same episode has Leela note that they should try to talk like Fry, since he was from around this time period. Needless to say, that fifty-plus year difference still made her incomprehensible.
 * An episode of The Batman features future archaeologists excavating the Batcave. They find a picture of a young Bruce Wayne with his parents, and logically, but of course, incorrectly, conclude that Thomas Wayne was Batman, and that young Bruce was "The Red Robin". They also conclude that Oracle's wheelchair (interestingly, Barbara Gordon's transformation from Batgirl to Oracle has not occurred yet in The Batman's continuity) belonged to Alfred. An interesting look at how perfectly reasonable assumptions on the part of archaeologists can be way off base.
 * This premise was strikingly similar to an issue of Amazing Spider-Man (see Comics section on this page) written in 1998. Heck, the investigative duo of the future showcasing the inaccuracies in both stories were also a black man and a white woman. What's funnier is that a lot of the missteps in the Spider-Man comic were Shout Outs to Batman, such as trophies and themed vehicles.

Real Life
"L.N.Gumilev: He called proof only a text containing precisely formulated information, but not considerations about the subject raised. Of course, I did not agree with him. In that case, of course, I would have been obliged to assert that Prester John ruled in the "Three Indias"! […] We have not taken primary information as a standard, but first order generalisation obtained earlier as a result of precise analysis of details."
 * Most of what historians have discovered about past centuries has been revised when new facts were discovered.
 * When occasionally people dug up dinosaur skeletons in the centuries before the 19th century they believed they had found the remains of animals that didn't survive Noah's flood.
 * Originally archeologists thought that the dinosaur species iguanodon wore a horn on his head. Later it was discovered that this "horn" was actually part of his thumb.
 * Many older visual representations of Ancient Greece or Rome show temples and buildings that are complete white, just like the ruins of these temples look today. Actually: back then all temples were painted in bright colors.
 * Historians in past centuries are very untrustworthy. They left us documents which are usually highly subjective. As a result some historical characters are now remembered as idealized heroes, while others are depicted as villains. Every time a ruler took a kingdom by force he made sure his predecessors were written off as tyrants, while his own regime was of course paradise.
 * Before the age of photography almost every visual representation was made years later, since it was impossible to capture something on the moment it happened. This allowed artists to fantasize their own ideas of how a certain person or historical event looked. Even paintings made by eye witnesses or while the subject was present to pose are dubious, since artists were forced to idealize or romanticize everything according to their patrons' wishes.
 * It doesn't help that the whole idea of "History" as a record of stark fact is a fairly modern notion. The Romans (and most cultures before them) had their own written histories of how their empire came to be, and these histories included myth and legend that were known to be myth and legend at the time. Like, for example, their founders Romulus and Remus being Raised by Wolves. Even at the time it was known to be very unlikely, but the story was treated as factual due to differences between their culture and modern culture making it a "Rule of Cool" situation for them.
 * Turning stories into political pamphlets was in fashion long before yellow journalism. And even when chroniclers try their best to convey the facts, everyone has a particular perspective and there's no way to tell how much of Confirmation Bias is there using only the text itself.
 * If future archaeologists applied the same ideas to us as we do to past civilizations they could conclude that "Kellogg's" boxes were some kind of religious icons, because it's the same word written exactly the same way, along with depictions of various "gods" (cartoon animals) and "offerings" (cereals).
 * Or perhaps future archaeologists will find caches of internet forums and conclude that all US presidents from Reagan to Obama were actually secret members of the Nazi party.
 * That was the concept of the Swiss exposition "futur antérieur", with how archaeologists of the Fifth Millennium might interpret 20th century society based what few archaeological remains would be conserved. The expo proceeded to Lampshade the guesswork and conflation which sometimes occur in the historical reconstruction, as well as our tendency to link every little artifact with religion. Highlights include conflating the victory pose of sportsmen and that of a crucified Jesus; garden dwarves interpreted as statues of important leaders or priests (pottery conserves well) and motherboards reconstructed as 3D city maps.
 * The exact same concept was used in the David Macaulay book Motel of the Mysteries (See Literature example above.)
 * The Bible, of all things, underwent this sort of thing in 17th century Japan. With Christianity outlawed and European missionaries expelled or worse, the few thousand Japanese Christians (or Kakure Kirishitans) left had to worship in secret. Problem: there wasn't a Japanese translation of the Bible. So they wrote their own, with half-forgotten Catholic ideology and already badly-translated, misremembered stories that had been passed down: hence in "Beginning of Heaven and Earth", "Deusu" creates "Adan" and "Ewo" in a Japanese Garden of Eden. The "Biruzen Maruya" is impregnated when Deusu, in the form of a butterfly, flies into her mouth. Pontius Pilate is distilled into Ponsha and Piroto. Jisusu proclaims: "The person who eats his rice with soup every morning is the one who will betray me." Maruya's friend composes a prayer at the River Abe (Ah-beh) - "Maruya, full of grace, to you I bow." Consequently, the prayer becomes known as the "Abe Maruya."
 * There is another theory which suggests this has already happened.
 * Weirdly, a combination of archaeology and a more careful attitude towards history can invert this trope: we now know more about the way people actually behaved in places like ancient Egypt than we did a few centuries ago. Of course, we're still probably getting a lot wrong, but looking at some of the misconceptions in old history books makes it clear that this trope can run both ways.
 * The science of numismatics (study of money) can invert this trope for future archeologists too. A future archeologist would only have to dig a lot and he would probably find thousands of different loose coins, tokens and medals all made from metals. He might even find entire coin collections, or entire commemorative coin boxsets. This would mean that a future archeologist would be able to trace most historical rulers, events and figures to their right place and time. This is incidentally how we know so much about the late Roman empire.
 * Another good source of historical information would be commemorative and memorial plaques, grave-stones and decorative dishes.
 * A popular joke is that North Korean children learn that Kim Jong Il invented electricity, the bicycle, film, etc. Whether these children actually are told this or not is for the well-traveled to determine.
 * Although they actually do make the claim that he invented hamburgers, as introducing Western products is difficult for a government that wishes to maintain hatred of the West.
 * Really, almost everything we know about history might fall into this. We assume what little we have about ancient civilizations is true and common. However, with paper being incredibly valuable and literacy increasingly rare the farther back you go, it stands to reason the things that were written down might have been unusual rarities, rather than the norm we might assume.
 * The fixation on paper as the only way to record things is a pretty modern thing and usually a huge mistake. A lot of what's known about ancient Rome, for instance, is from crudely scrawled, badly spelled graffiti. And literacy is very dependent on the specific culture and time period, often proportional to general standards of living. The good historians and archaeologists, at least, can attempt to compensate for differing literacy rates.
 * Luckily for the people of the future, documentation of world events has become more widespread and redundant in the past couple of centuries, making it more likely for future historians to get what happened correctly. At least, we can only hope.
 * On that note, historians of the future will love Wikipedia. . .if they still speak the same languages, that is.
 * And IF subjective contributors or unfunny jokesters ever quit adding nonsense or bad facts to the site!
 * There's also the not-inconsequential efforts of people throughout history attempting to shape it for their current ends. Monuments are especially vulnerable to this. For example, there have been groups active for over a century erecting monuments praising the Confederacy in areas that leaned towards the Union.
 * On the other hand, even in places that actually seceded, some Confederate monuments get vandalized by people who currently disagree with some of their policies.
 * A less extreme present-day example: There's a nontrivial number of people (outside the fandom's Kayfabe, that is) who think Sherlock Holmes was a real person, presumably because the series has just the right combination of age, popularity, lack of Speculative Fiction elements, and Literary Agent Hypothesis to encourage such things.
 * Give it a few centuries and there might be a number of people who take the Star Trek future history as fact!
 * Here is a list of things that they'd get wrong.
 * A real and utterly unlikely example: Pope Joan, the Englishwoman who not only allegedly became Pope, but whose tale was widely believed right into the 19th century. Of course, anti-Catholic prejudice probably had something to do with that.