History Main / ImposterForgotOneDetail

* ''Series/Lucifer2016:'' In season 5A, Lucifer's EvilTwin [[ArchangelMichael Michael]] impersonates his brother basically to ruin his life. There are a lot of little things that make Lucifer's friends think he is NotHimself, but he's always able to explain the discrepancies away. Except he doesn't know that Lucifer's feelings for Chloe make him vulnerable, meaning he isn't NighInvincible. Chloe uses this as an ImposterExposingTest, shooting Michael in the leg. When he removes his hand and reveals no blood, her suspcisions are confirmed.
-->'''Chloe:''' Once, I shot Lucifer to prove he was the devil and now I'm shooting you to prove you're not.

* At one point in ''VideoGame/MetalGearSolid3'', you have to infiltrate Groznyj Grad disguised as a local General named Raikov (who looks suspiciously like Raiden from [=MGS2=]) and to Snake's credit, once you knock him out, steal his clothing, and wear a latex mask of his face, no one is any the wiser. Where it falls apart is when he encounters Volgin, aka Raikov's ''lover'', who greets him by grabbing his crotch and almost immediately figuring it out, though to be fair, there's no way Snake would've known that. In addition, when you're disguised as a soldier, you'll be found out if you neglect to salute other soldiers who do the same to you.

* In ''Anime/MagicalGirlLyricalNanohaAs'', when the masked men take on Nanoha and Fate’s identities, parts of their Barrier Jackets are not the correct color. This is likely because [[spoiler:cats, and -- by extension -- {{Cat Girl}}s, are {{colorblind|Confusion}}]]. Not that it really matters, since the person they were trying to fool had never seen Nanoha or Fate in their Barrier Jackets.

** A currently manga-only story (as the anime hasn't caught up to it yet) features the culprit being unmasked because A) he responds to a phrase that sounds like a person's name to someone who speaks standard Japanese like the Osakan Heiji and Kazuha (namely, recognizing it's a candy and telling the girls they shouldn't spoil their meals with sweets); and B) when given oversalted ramen, echoes Heiji and Kazuha's sentiments that it's "overspiced" (Osaka-ben speakers only really use the word "salty" to describe salt water and in food, call salt a spice).

* ''WesternAnimation/ExtremeGhostbusters'': In the episode "The Ghostmakers", the demon possessing Edwardo’s body eats sandwiches with mayonnaise in them (which the real Edwardo hates). The demon possessing Garrett’s body, however, takes the cake by doing something a paraplegic person can’t do: stand on his own two feet.

* ''Comcibook/GreenArrow2023'': Ollie learns that his bouncing around time and seperation from the Arrow Family was all arranged by an older version of him, who says this is the only way to avoid a BadFuture in which all his loved ones die. Future Ollie says he's meant to be alone; he should have died on the island and on some level he knows that which is why he never returned there. Present day Green Arrow shoots him in the eye for a RoboticReveal and says he goes back to the island all the time, he just never talks about it.

* ''WesternAnimation/PinkyAndTheBrain'': When Brain decides to take over the world by impersonating UsefulNotes/AbrahamLincoln, he's not worried that people will notice that he doesn't sound like the real Lincoln because Lincoln died before voice recording devices were invented and Brain doesn't believe there's any living person old enough to have heard Lincoln talk. The oldest living American proves him wrong about the last part.

** Happens when Envy fights Ling. The homunculus ends up on the ground, and as Ling gets ready to attack, Envy transforms into Lan-Fan to catch him off guard. However, [[spoiler:Lan-Fan had recently lost an arm but, having not seen her in said state, Envy's form has two]]. This is still enough to rattle Ling who freezes long enough for [[spoiler:Gluttony to launch an attack]].

* The ''Franchise/SpiderMan'' mini-series ''Spider-Man: Hobgoblin Lives!'', Peter and Mary Jane are conversing about Ned Leeds, the man they all thought was the original Hobgoblin. However, as they were doing so, Peter realizes something he should have had ages ago: if Ned Leeds was the real Hobgoblin, the assassins that came in and killed him would have been the ones dead because he would have had the Goblin Formula in him. That leads to everyone realizing they'd been had. Among other powers, uses of the Goblin Formura get a HealingFactor and have recovered from seemingly deadly injuries. [[spoiler:Ironically, Ned does come back from the dead during ''ComicBook/TheAmazingSpiderManNickSpencer'' era, where it was revealed he ''did'' take the serum, but it hadn’t taken effect until he died]].
* In a 1990s storyline, Peter Parker's parents Richard and Mary appeared to have returned years after being believed dead. All evidence indicated they'd been held prisoner in Russia and were accepted by everyone. Richard suggested they all go out to a dinner to celebrate the anniversary of May's wedding to Richard's brother Ben. May instantly knew something was wrong because while she and Ben had a public wedding on that date, they actually had gotten married first in secret a month before...and Richard and Mary had been there. This was the first clue for Peter to discover his "parents" were androids created by the Chameleon.
* In ''ComicBook/TheSmurfs'' comic book story "The Fake Smurf", Gargamel (and Hogatha in the [[WesternAnimation/TheSmurfs1981 1980s]] AnimatedAdaptation) was capable of creating a formula that can change him into the form of a Smurf...but one detail that was missing in the transformation was that his impersonation doesn't have a tail. Gargamel tries to correct this by gluing a fake tail onto his behind, but later on, the tail ended up falling off, and Gargamel was soon spotted and revealed to be the fake Smurf.
* Early in ''ComicBook/TheSuperiorFoesOfSpiderMan'', Boomerang figures out that [[TheMafia the gangster Hammerhead]] menacing him is actually a disguised [[MasterOfDisguise Chameleon]], because Chameleon!Hammerhead was talking in a stereotypical gangster accent, and while that is Hammerhead's signature trait, the real Hammerhead had actually dropped the quirk at that point.
* ''Franchise/{{Superman}}'':
** This is what pings ComicBook/LoisLane into realizing the Cyborg Superman isn't the real Superman in the "Reign Of The Supermen" arc of ''ComicBook/TheDeathOfSuperman'' - he casually mentions to ComicBook/{{Superboy}} that he wished he had better control of his powers when he was his age. Lois remembers that Superman didn't get his powers until he was an adult (in that continuity).
** In the ''Team Superman'' oneshot, a villain fakes Superman deciding to leave the Earth. His motivations make sense, his disguise fools Batman and even Martian Manhunter's telepathy ... And then Lois flatly tells Supergirl it wasn't him. "He said goodbye to me with the same warmth and affection as he did Jimmy Olsen. Whoever this is did their homework, but they didn't know the ''secret''."

** During one of the many attempts of the Evronians to capture [[PhysicalGoddess Xadhoom]]: after identifying her as a Xerbian, they lure her on a false Xerbian colony with the intent of tricking her into wearing a restraining device, but when a happy Xadhoom mentions their party should have a Xarghon and they don't know she sees through the ruse... [[{{Troll}} And amuses herself with their attempts at guessing what a Xarghon is]]. When the Evronians finally catch on, Xadhoom informs them that a Xarghon is a traditional Xerbian welcome dance that any Xerbian child would have known of and promptly blows them up.

* ''ComicBook/LaffALympics'': In "The Day the Rottens Won", Dynomutt figures out there's an impostor pretending to be Blue Falcon when he asks why Radley Crown didn't show up for the opening ceremony and the impostor, not knowing Crown and the Blue Falcon are one and the same, asks how he should know.
* Used in a {{Retcon}} StoryArc in the ''ComicBook/FantasticFour''. In 1984, the Thing's long-time love interest Alicia Masters started undergoing some changes in characterization. She soon switched allegiances from the Thing to the Human Torch, and she married Johnny Storm in 1987. In 1991, it was revealed that this "Alicia" was Lyja, a female Skrull agent. She was good enough in impersonating Alicia that none of the Fantastic Four, their allies, and most of their enemies figured out the differences. Except for the super-villain Puppet Master, who happens to be Alicia's stepfather/adoptive father and raised the girl from childhood. He could tell that his "daughter" was acting out of character and started investigating why. Forgetting that the woman she was impersonating had a parent who knew her better than anyone else, Lyja undermined a pretty good espionage scheme.
** A key moment in the above is when the Puppet Master visits the grave of Alicia's mother to find it's covered with grass, vines, and dead flowers. This indicates Alicia hasn't visited the grave in a long time which was the first true clue to the Puppet Master something was wrong as Alicia never went a week without going there.
** Puppet Master tricks the New Warriors into attacking the FF as a distraction so he can talk to Alicia. Truly blind as part of the disguise, Lyja reacts as if to a complete stranger which confuses Puppet Master. When the Torch arrives and identifies him, Lyja realizes her mistake as the real Alicia would instantly recognize her stepfather's voice.

* ''ComicBook/DCComicsBombshells'': Constantine tries to infiltrate the Nazis by dressing as one, but is found out because he was smoking an English brand of cigarette.
* In the Creator/MarkMillar series ''Prodigy'', super-genius Elliot Crane is recruited by CIA agent Rachel to stop an ancient conspiracy planning to invade Earth. Crane figures out the calculations they can use to invade via another dimension at which point Rachel shoots him, revealing she was in on the conspiracy and they were using Elliot's genius to unlock the code. Leader Tinker gloats on it all...only to realize that the "code" has given Elliot full power over their computers to destroy the invasion. When Tinker asks how Elliott knew Rachel was setting him up, Elliot responds that Rachel couldn't speak Bedouin when it was a prerequisite for any CIA agent in the area she claimed to have been stationed at. "If she was lying about that, she was lying about everything else."
* In a ''ComicBook/RichieRich'' story, butler Cadbury is replaced by an impostor. Richie realizes the deception when said impostor calls him "Richie" instead of "Master Rich", [[OutOfCharacterAlert something the real Cadbury would never say]].
* In ''ComicBook/SonicTheHedgehogIDW'', this is a reoccuring problem for the shapeshifting Mimic the Octopus. While his disguises are mostly convincing, he always messes up some detail in the way they look or act, which gives him away. For example, his impersonation of Sonic has the wrong eye color and he refers to himself as "Sonic ''T.'' Hedgehog" instead of "Sonic ''the'' Hedgehog".
* In ''ComicBook/BatmanHush'', it seems like Jason Todd has [[BackFromTheDead returned from the grave]] to get revenge on the Caped Crusader. However, Batman deduces that it's actually the shapeshifter Clayface impersonating Jason--namely because he never refers to Batman as "Bruce." Jason was one of the few people in the world who knew the Dark Knight's secret identity, and Batman correctly reasons that the ''real'' Jason would use that knowledge against him.

* In most ''VideoGame/{{Hitman}}'' games, Agent 47 can disguise himself as an employee/guard to help him get in restricted zones. However, despite his amazing ability to blend in, the detail he can't duplicate is their behavior, leading him to get caught if he lingers. Any time 47 has to interact with his targets in disguise, due to his "[[TykeBomb up]][[CloningBlues bringing]]", he barely knows how society functions and gives off a creepy vibe - the one exception is disguising as a Catholic priest, since he actually has trained to enter the clergy.

* [[spoiler:Your clone]] in the ''Citadel'' DLC for ''VideoGame/MassEffect3'' has more sort of forgotten every detail beyond "has the Normandy" and "wears an N7 badge"; doesn't have the charisma, doesn't have the flexibility, doesn't have the compassion, doesn't have the cybernetics, doesn't have a clue. You can actually point out, during the final confrontation, that there is ''no way'' the impostor is going to be able to fool, say, Admiral Hackett for even a minute. The impostor ''did'', to their credit, remember that [[spoiler: despite being [[CloningBlues a clone]]]] they would need to replace the original's recorded fingerprints with their own, and arranged a complex scheme to do just that.

* During World War II, any attempt by the Germans to pass forged documents to the Soviets ended up being exposed. The fakes were recognized even by ordinary soldiers. After a long time, it became a well-known secret. Paper clips in the Soviet Union were made of ordinary steel (and in wartime, they rusted), and German paper clips (including the forgery of Soviet documents) used stainless steel.

* An episode of the ''Anime/{{Pokemon}}'' anime involved a Ditto that could transform into other Pokémon flawlessly, except that it couldn't match their faces. While it was originally an example of this trope, later appearances of Ditto in the anime show ''all'' Ditto looking like this when they transform.

* In ''[[https://www.fanfiction.net/s/3482033/1/Shadow-Realm-PI Shadow Realm PI,]]'' a fic set in the world of the Duel Monsters cards, someone frames the Amazoness monsters for her crimes by attacking people using an Amazoness Blowpiper's blow darts. One of her surviving victims realizes she was a fake because she was wearing high heels while the Amazonesses [[DoesNotLikeShoes go barefoot]].

* After killing the BigBad in the ''Film/TotalRecall2012'' remake, Doug wakes up in an emergency vehicle with Melina holding his hand. He then notices that she's missing the bullet wound scar on her hand, forcing his "wife" Lori to reveal herself (using a holographic device he used earlier) and attack him.
* InvokedTrope in the 1977 version of ''Film/TheManInTheIronMask''. Minister Fouquet is confronted with King Louis and his identical twin dressed exactly the same, except his sash is the wrong color (a detail the conspirators changed so they'd know who their man was) so Fouquet has him arrested. He's the twist--the conspirators knew Fouquet was on to them, so arranged for him to be told earlier that the king had changed his mind about the color of his sash. Fouquet has actually arrested the real king.

* ''Film/TheDarkSideOfTheMoon'': Satan apparently forgot or didn't care that his host body is allergic to sugar in his coffee. It's down to just two crew members by that point, so the only remaining human immediately starts to prepare for the final confrontation.

* ''Last Days of Mussolini'' (1974). German troops try to smuggle Mussolini through a partisan checkpoint by dressing him as a German soldier, but he's still wearing the trousers of a high-ranking officer.

* In ''Film/WildWildWest'', Artemis Gordon has a nearly foolproof disguise as President UsefulNotes/UlyssesSGrant (the fact that the same actor plays both helps) but West quickly knows it's not Grant because he was wearing the wrong school ring. It doesn't help that "Grant" keeps going on and on about [[ButHeSoundsHandsome how great an agent Gordon is.]]

--->'''The Doctor:''' Reduced iris contraction, slight thinning of the hair follicles on the left temple, and... frankly, you ''smell''. You might as well have been wearing a T-shirt saying "Clone". Although... [[TwinThreesomeFantasy maybe not in front of]] [[AnythingThatMoves Captain Jack]].

** Directly after this incident, Sasuke makes up a long and complicated password to serve as the one detail. Orochimaru later disguises himself as Naruto and recites the password perfectly. Sasuke immediately realizes that he's an impostor, as he forgot that Naruto was an IdiotHero who could ''never'' have gotten the password correct on his first try ([[KansasCityShuffle this being Sasuke's plan with the password all along]]). Sure enough, when the real Naruto appears, the first thing he does is ask for Sasuke to repeat the password.