History Main / ImposterForgotOneDetail

** In a filler arc, Naruto, Kiba and Hinata invoke this trope to distinguish themselves from their impostors. They have Hinata, who injured her leg, stay behind, and have the real Kiba be identified by having Akamaru with him, and the real Naruto identified by the chest.

** In "Tooth and Claw", the Doctor accidentally ends up in the Scottish moors. The moment he realises they're in Scotland he switches to a Scottish accent and pretends to be a Scottish physician [[ContinuityNod named Dr. James McCrimmon]] so that Queen Victoria doesn't shoot him. Later at dinner he slips back into an English accent and Victoria calls him out.

[[AC:{{Film}}]]
* In ''{{Megamind}}'', Megamind blows his cover in one scene by pronouncing Metro City as "Me-trocity". He just barely avoids doing the same earlier in the film.
* In ''TheSorcerersApprentice'', sorcerers powerful enough to do so have the ability to morph into whomever they wish. When Drake Stone, a less experienced Morganian, attempts to trick Balthazar into giving him the Grimhold while disguised as Dave, he accidentally lets his British accent slip, giving himself away.
* In the movie ''DeadAgain'', a man claims to be the fiance of an amnesiac woman and he presents a glove as proof. The glove seems to match the woman's except for one problem: it's for the wrong hand.

[[AC:FanFiction]]
* In the Fresno, [[{{California}} California-based]] Doctor Who Audio Dramas' continuity, the [[TomBaker David]] [[{{Expy}} Segal]] [[TheNthDoctor Doctor]] traveled with mute reporter Susie Jo Parker. Although mute, Susie Jo did speak. Usually when an impostor took her place and didn't research her very well.

* In ''WesternAnimation/JackieChanAdventures'', Jade is able to spot Paco as a magical clone because he pronounces her name correctly, unlike the real Paco, who always pronounced it "Yade" (because J is pronounced like Y in Spanish).

* In the Fresno, [[{{California}} California-based]] Doctor Who Audio Dramas' continuity, the [[TomBaker David]] [[{{Expy}} Segal]] [[TheNthDoctor Doctor]] traveled with mute reporter Susie Jo Parker. Although mute, Susie Jo did speak. Usually when an impostor took her place and [[DidNotDoTheResearch didn't research her very well]].

** In an earlier arc, Orochimaru masquerades as Naruto in order to infiltrate Team 7. When Sasuke asks for the password, Orochimaru!Naruto says it without problems. This is an inverted trope because Sasuke later states that Naruto would have never gotten the password correct in the first try.

* In ''WesternAnimation/JackieChanAdventures'', Jade is able to spot Paco as a magical clone because he pronounces her name correctly, unlike the real Paco, who always pronounced it "Yade."

** Although Adam did better impersonating Jamie than Jamie did impersonating Adam, in part because Adam frequently mimics Jamie for amusement.

* In ''WesternAnimation/MyLittlePonyFriendshipIsMagic'', it's the principle failing of [[spoiler: the Changelings]], as "getting into character" isn't their strongest suit.

* In ''TsubasaResevoirChronicle'', a minor antagonist tries to protect himself from Syaoran's attacks by claiming to have taken Sakura hostage. However Syaoran realises that the Sakura in front of him is just an illusion, since she calls him "Syaoran" instead of "Syaoran-kun".

* The "Datalore" episode of ''StarTrekTheNextGeneration'' made clear that Data doesn't use contractions, while Lore can. In an inversion, even though Data is the person Lore is copying, Data was the younger of the two, and so technically "lost" the ability to use contractions. (In a now-infamous mistake, the "real" Data used a contraction in the episode's final scene, and depending on who you talk to it either wasn't noticed or they didn't have time to do another take. This also launched a thousand, or at least half a dozen, wild mass guesses when it was noticed.)

* Nicely done in ''Series/{{Merlin}}'' when Morgana [[BackFromTheDead resurrects Lancelot]] from the spirit world, [[BrainwashedAndCrazy brainwashes him]], and sends him to Camelot in order to stir up trouble. However, Merlin catches him out by phrasing a sentence that casually references the use of magic - Lancelot being one of only two people in Camelot who ''knows'' that Merlin is a warlock. But because Morgana doesn't know, then fake!Lancelot doesn't know either, and responds in a manner that makes no sense to one who ''should'' be aware of Merlin's secret.

* Nicely done in ''Series/{{Merlin}}'' when Morgana [[BackFromTheDead resurrects Lancelot]] from the spirit world, [[BrainwashedAndCrazy brainwashes him]], and sends him to Camelot in order to stir up trouble. However, Merlin catches him out by phrasing a sentence that casually references the use of magic - Lancelot being one of only two people in Camelot who ''knows'' that Merlin is a warlock. When the fake Lancelot doesn't respond in the expected manner, Merlin knows that something's wrong.

* In ''RedDwarf'' the impostor Lister can play the guitar really well. The real Lister only ''thinks'' he can.

* Played literally in ''{{Mythbusters}}'' when Adam and Jamie tried to disguise themselves as each other - despite much effort, vocal cues and accents ended up being the weakest part of the ensembles. Imposter Jamie did indeed lack the accent.

* In ''MyLittlePonyFriendshipIsMagic'', it's the principle failing of [[spoiler: the Changelings]], as "getting into character" isn't their strongest suit.

** In "Tooth and Claw", the Doctor accidentally ends up in the Scottish moors. The moment he realises they're in Scotland he switches to DavidTennant's natural Scottish accent and pretends to be a Scottish physician [[ContinuityNod named Dr. James McCrimmon]] so that Queen Victoria doesn't shoot him. Later at dinner he slips back into an English accent and Victoria calls him out.

* The former Trope Namer is in the ''Series/DoctorWho'' episode "The Faceless Ones", when Jamie has been captured by the Chameleons--and Chameleon!Jamie does not have his Scottish burr.

* In ''MyLittlePonyFriendshipIsMagic'', it's the principle failing of the Changelings, as "getting into character" isn't their strongest suit.

* [[http://en.wikipedia.org/wiki/Shibboleth Shibboleths]] are OlderThanDirt originating from at least 1000BC and has been used throughout history to detect impostors (or people on the genocide list).