Cover Identity Anomaly

"Alright, you look like a future pedophile in this picture, number one. Number two: It doesn't even have a first name, it just says McLovin!"

Homer: Hello, my name is Mr. Burns. I believe you have a letter for me.
Postal Worker: Okay, Mr. Burns, what's your first name?
Homer: [beat] ...I don't know.

— The Simpsons, "Blood Feud"

This trope is when a character, in disguise or otherwise pretending to be someone else, doesn't know some basic piece of information about the person they're pretending to be. This could be because they didn't research the identity enough, or maybe the disguise and cover identity were done in a rush and they didn't think all the way through.

A quick-thinking character might be able to bluff their way out of the situation, either through a Line-of-Sight Alias, using their Real Name as an Alias, or simply pulling the Bavarian Fire Drill. This can backfire if they say the wrong thing, mess up the Trust Password, or if the person they're trying to fool is already suspicious. Otherwise, Hilarity Ensues as the character either tries to play it straight (i.e., they've somehow forgotten their first name, birthdate, hometown, etc...) or just tries to awkwardly escape. In drama, this might lead to a tense situation where the character is found out and has to escape without being caught.

Compare Stereo Fibbing, for when two characters have to make up a lie on the spot to get out of this situation. Contrast Conveniently Unverifiable Cover Story. Depending on the situation, this trope may even be an Exaggerated Version of Imposter Forgot One Detail; but whereas with that trope the detail-in-question is usually something relatively minor that anyone can overlook ^note  Such as, say, an imposter walks normally whereas the real person has a small limp , this trope would be where the detail is so big it’s as though the imposter utterly Failed a Spot Check in their research/preparation... if there was any to begin with^note  Where the imposter walks at all, but the real person lost both legs and uses a wheelchair . Can cause a Legendary Impostor to be exposed.

See also Imposter Forgot One Detail, Spotting the Thread, Minor with Fake I.D..

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Examples:

Anime & Manga

• Kamen no Maid Guy has an example where the twenty-something Tsurara tries to infiltrate Naeka's school as a student. The usually ditzy Naeka asks her which Eastern Zodiac year is her birthday in. For people in a heavily Chinese-influenced country, your own zodiac year is something you already know and can be answered without thinking. Calculating your supposed birth year from a fake age and come up with zodiac year for it, though, would take several seconds and some finger-counting.
• In Lupin III: Dead or Alive, Olèander is able to see through Lupin's disguise because of how it felt to kiss Pannish. In the dub, Lupin jokes he needs more practice. In the Sub, it is because Pannish never smoked. She doesn't seem upset about the disguise and continues to work with him afterwards.
• Inverted in the first clash (chronologically) of Shinichi Kudo and Kaitou KID in Magic Kaito. Shinichi instructs the police officers to verify each other's identities by asking for name, date-of-birth, and driver's license number. When KID successfully rattles off all three, they identify him as an imposter. The anomaly isn't that he doesn't know a basic piece of info, but that he did know something most people would never have memorized.
• In Mobile Suit Gundam 0080: War in the Pocket, Bernard Wiseman tries to sneak into the Federation base holding the NT-1 "Alex" by talking about the weather in Sydney, Australia. However, Bernie mentions winter in December, where, with Australia being in the Southern Hemisphere, would actually be in the summer. Later retcons following the anime's release would make this example even worse as Sydney was designated the site of original anime's infamous Colony Drop.
• Naruto: Team 7 tries their utmost to avoid this when they have to meet Sasori's spy whilst disguised as Sasori. It actually works; the spy doesn't realize he's dealing with an imposter...he was just intending to double-cross Sasori anyway.
• SPY×FAMILY: During a mission to retrieve a secret schematic capsule at the Berlint Aquarium, Loid Forger aka. Agent Twilight (disguised as a worker) encounters a terrorist retriever claiming to be a professor at the University's Marine Biology Lab, even presenting an ID. Of course, being a master spy who knows every trick of the trade, Agent Twilight examines the ID and easily sees it as a fake (it even smears with water). The terrorist immediately panics once his cover is blown; it apparently never crossed his mind to have an ID of passable quality.
  Agent Twilight: "This ID is fake. Not to mention extremely poorly made."
• On Yu-Gi-Oh! when Joey is set to duel Marik, the villain sends his henchman Odion to duel in disguise as himself. After the duel Joey, in a rather uncharacteristic example of Genre Savvyness, notices that "Marik" was as fierce and skilled as he expected, but fair: he didn't cheat, he didn't use any Shadow Game shenanigans, he didn't use his Millenium Rod for an advantage, he had no traps on the ready, or anything, and instead relied entirely on his skill as a duelist and on the strength of his deck. Joey surmises that Odion isn't really Marik, noting how there's no way the real Marik would have dueled so honorably, and there is no way in hell someone like Marik would congratulate someone for beating him.

Comic Books

• In Combat Kelly and his Deadly Dozen #8, Laurie and Kelly infiltrate a Nazi medical facility by posing as a female doctor and her driver. Laurie took the real doctor's identity papers off her when they ambushed her, but failed to check them and so failed to realize that they contained a photograph. As a result, her cover is blown the first time a guard checks the papers.
• Paperinik New Adventures:
  • When a group of Evronians (who just don't get the point of many expressions of emotions and tend to ignore them) disguise themselves as Xerbians to trick Xadhoom into wearing a restraining device they have no idea of what a Xarghon is. A Xarghon is a traditional Xerbian welcome dance that any child on their homeworld would have known about, leading to Xadhoom (who really loves dancing to boot) to see through the ruse... And amuse herself with their attempts at guessing what a Xarghon is before she blows them up.
  • When Paperinik infiltrates Belgravia disguised as Grigorji Grimka, son of the president, to try and find out who in the government betrayed and tried to kidnap him, he was not informed that Grigorji had a large and irascible fiancée who is allergic to flowers and he doesn't like, thus allowing her to see through his disguise when he's nice and offers her flowers (thankfully she wasn't the traitor and limited herself to see who the impostor was and why he was there, leading a group of loyalists to the rescue at the right moment). This is caused by Grigorji, who is an idiot, purposefully leaving this detail out alongside the fact he keeps two lions as pets while telling his lover, who is actually one of the traitors, that he's still in America and the Grigorji coming home is an imposter.
• The Mark Millar series Prodigy has genius Elliot Crane recruited by CIA operative Rachel to stop a cult from launching an inter-dimensional invasion of Earth. When Crane figures out the formula for it, Rachel shoots him and it turns out she's in league with evil boss Tinker. But when Tinker uses the formula, it gives Crane access to their systems to thwart the invasion. Crane explains the pair had gone to massive lengths to give Rachel a seemingly perfect cover...but missed the fact she couldn't speak Bedouin when it was a prerequisite for any CIA operative in the area she claimed to have been stationed in. "If she was lying about that, she was lying about everything else."
• Spider-Man: In the early 1990s arc from The Amazing Spider-Man (1963), where Peter Parker's parents returned from the dead, May realized they were imposters when they refer to the wrong date for their anniversary, indicating that they somehow didn't know about their secret wedding several months prior.
• In a Supergirl (2005) Annual, Supergirl tries to pass herself off as Lana Lang's niece when a cop questions her. She realizes too late she doesn't even know what her alleged job is.
• Wonder Woman (1987): "Donna Milton" desperately clings to her name and past, but when Diana asks if she can remember what color her childhood home was painted, and some other things that should have been easy for her to recall the Memory Gambit starts falling apart making it clear she really is Circe.

Comic Strips

• Dick Tracy: In the "Spinner ReCord" arc, the Police Custodian claims to be a collector of rare first print records to explain his acquaintance with record dealer Spinner. However, when Tracy searches his house, he discovers that the Custodian doesn't even own a phonograph, let alone records.
• Played for laughs in a FoxTrot strip; Paige tries to forge her father's signature on an excuse note to get out of gym class, but her teacher catches on because the I's are dotted with little hearts.
• Knights of the Dinner Table:
  • Brian's character gets into trouble attempting to enter a walled city during a Grunge Warrior game when he presents the guards with forged papers that identify him as an ambassador from a country that ceased to exist 30 years previously.
  • Bob and Dave's characters disguise themselves as acolytes to sneak into a temple and steal a (supposedly) valuable relic. When a suspicious guard asks them basic questions of temple doctrine, Bob's response is "I tell him we've taken a vow of silence."
• In one arc of Liberty Meadows Ralph (a midget circus bear) tries to buy guns using a fake ID that identifies him as a 58-year-old black woman from Missouri. He accuses the store owner of being a commie as he's tossed out.

Fan Works

• New Vegas Showtime: To cover for his Japanese accent and lack of local knowledge, Akira initially claims to be from a Vault populated only by Japanese-Americans with a stash of Japanese media. When the Courier asks which number the Vault was, the first number Akira thinks of is 22; unfortunately for him, the Courier has been to Vault 22, which is both long abandoned and completely overrun by mutated plantlife. This, along with his outfit (that doesn't resemble a Vault suit at all) and airsoft gun (which shoots plastic, a massive waste of oil in the Wasteland) puts enough holes in his story that he quickly abandons it in favor of the truth.
• In the Star Wars Rebels story A Sword to Pass, when Tristan and his father find the saboteur in the Industrial district the man identifies himself as a member of House Vizsla by showing the insignia on his armor. However, Tristan points out that the insignia is upside down. The saboteur questions this showing that he is in fact not a member of House Vizsla.

Films — Animation

• The title character of Mulan does this when asked her name. Her family name (which she must use as part of the cover story) is Fa, but she hasn't thought of a personal name, leading to a very awkward conversation where Mushu tries to secretly help her come up with a name. One of his suggestions is Ah Chu, which would have lead to the cover identity being Fa Ah Chu.
  Mushu: Gesundheit. [laughs] Oh, I kill myself.
• In Wreck-It Ralph, Ralph tries to pose as a candy cane tree inspector while quizzed by Vanellope, but she sees through this lie immediately because he clearly knows nothing about her game world.

Films — Live-Action

• In Ace Ventura: Pet Detective, Lois Einhorn is revealed to the audience as Ray Finkle when she yells in a man's voice at commentary of the "Kick Heard Round the World" that drove him over the edge. She's alone when that happens, though.
• Averted in Argo. While rehearsing their cover identities as Canadian film producers, one of the escaped hostages, reading off his fake passport, pronounces Toronto "Toe-ron-toe". Tony points out that natives of the city don't pronounce the second "t".
• In Die Hard with a Vengeance: A German disguised as a New York cop makes a few slips of colloquial language as he talks to John McClane. He says "it's raining dogs and cats" instead of "cats and dogs" and calls an elevator a "lift." These seem to put McClane on edge. He then spots another cop wearing the badge of one of his co-workers. When he asks a group of the cop's comrades what the lottery numbers were last night, no one knows. It had been established in the first scene that the cops in McClane's circle play the lottery, meaning these guys are imposters.
• In Firestorm, Jesse becomes suspicious that the firefighters he encounters are not what they seem because they climbed to a ridgeline during a forest fire. Any firefighter knows that fire moves faster going uphill, and going up a hill in a fire is a good way to get trapped.
• Inglourious Basterds has an example with disastrous results. In the tavern scene, Major Hellstrom is already suspicious of Lt. Hicox. Hicox manages to avoid this until he orders three Scotches using his index, middle and ring fingers, as opposed to his index, middle and thumb, which is custom in Germany. This blows his cover and results in everyone in the bar except Hammersmark and a Heer grunt dying in a 15 second shootout.
• Little Woods: Deb's plan to get an abortion involves a faked ID. When she has to flee the forgers and so doesn't get an ID with her picture, Deb has to settle for trying to mimic another women's ID. The secretary at the clinic catches the deception, but lets her pass anyway.
• In The Master of Disguise, Devlin Bowman tells one of his lackeys that his wife called. When the lackey thanks him for passing the message, Devlin reminds him that he's not married and pulls off his mask, revealing him to be Pistachio. Pistachio then asks how Devlin knew it was him, and Devlin points out that Pistatio is still wearing the shoes from his Cherry Pie Man disguise.
• The Mask of Zorro: Subverted. In Joaquin's first meeting with Don Rafael, Joaquin makes some errors in his cover, but manages to come up with a plausible reason for each of them.
• In Murder on Flight 502, Mona Briarly becomes suspicious that Father Thomas Healey is not a real priest when he makes no move to offer last rites when Dr. Walker is working to save Otto Gruenwaldt from a potentially fatal heart attack. Later, she speaks to him and gets a look at his hands and observes he wearing nail polish.
• Nite Tales: The Movie: In "Storm", the fake cop—who has already made several errors in evidence handling—says that there is an "ABP" out for James, who actually is an undercover cop points out that the term is "APB", as it stands for All Points Bulletin.
• In No Man of Her Own, Helen tries to convince her doctors that she isn’t Patricia Harkness, but they think she's just confused because of the train crash she survived. The Harkness family then takes her in (never knowing what Patricia looked like). She decides to go along with it because she’s penniless and has a newborn baby in tow, but she makes a lot of simple mistakes about the Harkness' son (Hugh) who Patricia was married to.
• In Rambo: First Blood Part II, Rambo immediately notices a hole in Murdock's backstory and points it out to Colonel Trautman:
  Rambo: Remember Murdock said he was with the Second Battalion, Third Marines in Kon Tum in '66?
  Trautman: Yeah.
  Rambo: The Second Battalion was at Kud Sank. You're the only one I trust.
• In Romy and Michele's High School Reunion they are pretending to be "successful businesswomen" to impress people. It is only when a waitress asks them what business they are in that they realise they may have neglected a vital element of their cover story. During a dream sequence, Michele actually supports her cover by rattling off a complex but plausible method of developing the adhesive for Post-It Notes, which they claim to have invented. Interestingly enough, it wasn't scripted - Lisa Kudrow improvised thanks to actually having a degree in Biology.
• In Run for the Sun, Van Anders is claiming to be a Dutch archaeologist, but when Kate goes through the hacienda's library, she doesn't find a single book on archaeology.
• In the final sequence of Stalag 17, Sefton confronts Price, the Nazi double agent in the PoW barracks. Price stands up pretty well to questioning, until Sefton asks him when Pearl Harbor was bombed. He knows the right day and time, but forgets about the time difference. He gives the time in Germany, when it was about six hours earlier in the US.
• Star Wars: A New Hope:
  • Han and Luke are disguised as stormtroopers aboard the Death Star, to rescue Princess Leia, when they're forced into a shootout with some real stormtroopers. After killing them, Han rushes to a com unit to try and fool the troopers on the other line that nothing's wrong, and the following conversation takes place:
    Han: [sounding official] Uh, everything's under control. Situation normal.
    Voice: What happened?
    Han: Uh, we had a slight weapons malfunction, but uh... everything's perfectly all right now. We're fine. We're all fine here now, thank you. How are you? [winces after saying that]
    Voice: We're sending a squad up.
    Han: Uh, uh.. negative, negative. We had a reactor leak here now. Give us a few minutes to lock it down. Large leak, very dangerous.
    Voice: Who is this? What's your operating number?
    Han: Uh...
    [Han shoots the intercom]
    Han: [muttering] Boring conversation, anyway... [shouting] LUKE, WE'RE GONNA HAVE COMPANY!
  • Leia: Aren't you a little short to be a stormtrooper?
• In Stranded in Space, a crashed astronaut named Stryker is recovering in a hospital but isn't allowed to leave. At first he assumes he's being held prisoner by Russians who are pretending to be Americans, so he tries speaking Russian to Dr. Revere, but Revere claims to not speak the language. Still suspecting a trick, Stryker tries another tactic:
  Stryker: Speaking of Boston, Dr. Revere ... any relation to Paul?
  Revere: (clearly puzzled) Paul ... Revere? No, I don't think so.
  Stryker: That's all right. Paul Revere wasn't much of a ballplayer.
  Revere: I'm afraid I'm as ignorant of sports as I am of other languages.
• Played with in the movie Superbad, where Fogell gets a terrible fake ID that only has the name "McLovin". (The fact that there's no first name is bad enough, but the signature on the license clearly says McLoving.) It actually appears to fool the cops, and they end up going on an adventure with the kid. Subverted in the end when they reveal that they immediately saw through the fake but wanted to have some fun and show him that not all cops are assholes.
• In Terminator 2: Judgment Day, after being rescued from the T-1000, John Connor orders the T-800 to stop next to a payphone, so he can warn his foster parents about the T-1000. Janell, his foster mother, answers the phone and sounds incredibly worried wanting to know where John is so she can go pick him up and bring him safely home. John tells the T-800, that Janell has never sounded so nice or concerned. The T-800 asks John to give him the phone:
  T-800: What's the dog's name?
  John: Max.
  T-800: [adapts John's voice] Hey, Janell, what's wrong with Wolfie? I can hear him barking. Is he OK?
  Janelle: Wolfie's fine dear, just fine. [sternly] Where are you?
  T-800 [hangs up phone, in his normal voice] Your foster parents are dead.
  [cut to John's foster parents' house; Janelle is revealed to actually be the T-1000, as his blade arm is impaling Todd through his mouth and the milk carton he was drinking from]
• Tinker, Tailor, Soldier, Spy. A Soviet military officer is seen saluting the cultural attache, despite the fact that he's a civilian with no war service. This causes the analyst who spots this to suspect that he's The Handler of a KGB mole, but her suspicions are not listened to and she's forcibly retired.
• In To Be or Not to Be, the German spy gives himself away by not knowing who Maria Tura is, despite her being a hugely famous actress in his supposed hometown.
• Trading Places: Ophelia disguises herself in lederhosen and claims to be from Sweden, clearly mistaking the country for Switzerland. When her conspirator Coleman notes the discrepancy in front of their mark, she insists, "Ja! From Sweden!" while motioning for him to just go with it.

Literature

• And Then There Were None: Blore (an ex-cop now working as a private detective) goes to the island under a false name and claiming to be from South Africa (his research consisting of reading a tourism pamphlet). The disguise lasts about as long as it takes for him to meet Phillip Lombard, who has actually been there, but it's a moot point very quickly since the recording identifies Blore by name and everyone quickly figures out it's him.
• The Executioner. Inverted in Brothers in Blood when a woman tells Bolan about a group of 'hunters' who are actually a hit squad hunting Bolan.
  "...dressed up in denims and huntin' caps and hikin' boots and so forth — nothing wrong with them, and that was what was wrong. They looked like they'd stepped out of an L.L.Bean catalog, outfitted up and ready to go. I say to myself, Miss Jane, here is a mess of folks trying to look like something they ain't."
• Flashman:
  • Flashman and the Great Game. Flashman is posing as a recruit for a native cavalry unit in India. Despite claiming that he has no previous military experience, the Old Soldier quickly spots him as a fraud because Flashman is unconsciously standing the correct distance from his desk, and has bridled his pony in the regulation manner. Fortunately this serves as an Infraction Distraction as everyone assumes he's just on the run from a tribal blood feud, rather than a British officer in disguise.
  • When Flashman is posing as a British naval officer in the United States, someone (young lawyer Abraham Lincoln) later points out several dinner habits a navy man would have that Flashman failed to emulate (being an army officer).
• Harry's Game by Gerald Seymour. The protagonist is a British agent posing as an Ulsterman, who's supposedly been away for years working as a merchant seaman to explain any unfamiliarities for the local culture. Unfortunately he gives himself away to his girlfriend when he complains about the cold wind when they're near a sea cliff, and she points out that he should be used to it as a sailor.
• Harry Potter:
  • In Harry Potter and the Chamber of Secrets, Harry and Ron use Polyjuice Potion to pretend to be Crabbe and Goyle to infiltrate the Slytherin common room but end up making a huge number of boneheaded mistakes: for one thing, they realize too late they don't know where the Slytherin common room is. They ask a passing student, but she's from Ravenclaw. Luckily Draco shows up and they follow him and are nearly busted when he asks them for the common room password but Draco suddenly remembers it. Other instances of them being out of character are when Harry didn't know what Azkaban was and when both of them forgot to laugh at a Daily Prophet article where Ron's dad gets in trouble with the Ministry. Luckily, Crabbe and Goyle are such idiots that Draco doesn't see any of this as out of character.
  • In the movie, Harry almost gives it away by still wearing his glasses. He quickly excuses them as reading glasses, causing Malfoy to stare at him skeptically and, courtesy of an adlib by Tom Felton, to remark that he didn't know "Goyle" knew how to read.
  • The specific example of the location of the Slytherin common room comes up again in Harry Potter and the Deathly Hallows, when Scabior says people have claimed to be Slytherins when caught by his gang of Snatchers but couldn't say where the common room was. Because of his previous experience, Harry can actually answer this question which throws Scabior for a moment, but not enough to let Harry go.
• InCryptid: In the carnival Annie is truly comfortable and at home among the carnies; so much so in fact that she forgets she's supposed to have only rudimentary knowledge of cryptids as Timpani. She slips and mentions her family in the present tense, and starts letting Antimony's knowledge leak out especially once she's taken a shine to Sam.
• The Looking Glass War: British agent John Avery is sent to Finland to retrieve the body and possessions of the late Mr Malherbe, who was actually a cover identity for a colleague. Avery claims to be his half-brother, but he's never seen Malherbe's fake passport - and when he's quizzed by the Finnish police it's obvious that he doesn't even know his supposed brother's age or date of birth.
• In Lucky Starr and the Oceans of Venus, David is contacted telepathically by something claiming to represent the V-frogs and making threats to humans. The voice appears to have little understanding of human tech by using words like "machines of shining metal". Then the voice uses the words "the quenching of a flame". A being native to the nitrogen-and-carbon-dioxide atmosphere of Venus would have just as little concept of a flame as of a spaceship.
• Nick Velvet: In "The Theft of Nick Velvet", the killer accidentally exposes himself while claiming to be an artist from Johannesburg and talking about the excellent southern light in his studio. As Nick points out, in the southern hemisphere, artists want northern light.
• Averted in On Wings of Eagles by Ken Follett. 'Bull' Simons insists that the EDS men he's taking out of Iran learn the details on their fake passports off by heart. Everyone thinks this is an unnecessary precaution until just before they reach the border when they're stopped at a guerilla checkpoint and grilled on these exact details.
• See You In November by Peter Stiff. The protagonist spends two months preparing for a mission into Zambia, going over every detail of his cover story. On arrival he instantly gives himself away as a foreigner by going to the chemist to buy a shaving brush. The chemist bursts into peals of laughter because he hasn't seen a shaving brush since Zambia became independent.
• Skulduggery Pleasant. Scapegrace has a problem that causes him to invent a twin brother, of course he gets every detail right and thinks of everything...except one of the names.
• A Song of Ice and Fire. While on her quest to find the fugitive Sansa Stark, Brienne of Tarth claims she's looking for her sister, but forgets to think up a false name for her. It's a moot point anyway, as most people can tell who she's looking for just from the description, given that she's rather high-profile (when the heir to the North is a suspect in the murder of the King, word gets around) and there's a lot of other people searching for her.
• Several of these in The Spycatcher's Omnibus by Lt. Colonel Oreste Pinto. In one case, Pinto is alarmed to discover a high-ranking British official who is a notorious ladies' man has got himself a new Sexy Secretary, a refugee from German-occupied France who did not pass through the routine security clearance. He has to do an ad-hoc interrogation there and then, with the official constantly demanding Pinto hurry up (despite the fact that such interrogations normally take days). Pinto suddenly has the idea of telling the woman to take off her shoes, which reveals her nice, soft feet — despite her claiming to have walked all the way from France over the mountains to Spain. The official is flabbergasted when Pinto informs him his secretary has just confessed to being a German agent.
• The Tommy and Tuppence novel N or M?
  • Tuppence is undercover as an "unofficial" agent at a seaside inn attempting to root out a German spy. She has made up her own elaborate back story where she has three sons, one serving in each branch of the military, who send her letters in secret code. At one point, she talks about her "own two", momentarily confusing her real-life twins with the made-up sons. When called on it by the inn's owner, she covers it by explaining that two of her sons were very close in age and spent more time together than with the third sibling.
  • Tommy, undercover at the same time, averts this; his background was made up by the intelligence agency he's working for to fit in neatly with his existing life and not be too elaborate to remember.
• In the Warrior Cats book The Darkest Hour, while trying to rescue some of Tigerstar's prisoners, Ravenpaw pretends to be a RiverClan cat and tells the guard, Jaggedtooth, that Tigerstar's summoned him and that he's supposed to take over as guard while Jaggedtooth is gone. Jaggedtooth is instantly suspicious because Tigerstar had declared that only ShadowClan cats can guard them. Ravenpaw simply says he'll tell Tigerstar that Jaggedtooth wouldn't come, and Jaggedtooth decides that if Tigerstar really did give a command then it's best to obey it.
• X-Wing: Wraith Squadron: Face Loran, in disguise as Captain Darillian, stumbles into one of these during a video call when Admiral Trigit uses a catchphrase from Imperial Intelligence doctrine, which Face doesn't recognize but Darillian should know instinctively. Face's bridge crew does put the definition up on a screen after a few seconds, but Trigit is still suspicious. Naturally, Face bluffs his way out of it, first by seemingly confessing the truth ("I'm not the Zurel Darillian you knew"), then by distracting Trigit with a tale of his unrequited love for Ysanne Isard, the previous head of Imperial Intelligence. Since Face as a Former Child Star actually got to meet Isard in person once, he's able to bring up a lot of details like the specific perfume she wore, which is enough to distract/convince Trigit. And at the end of his performance, it turns out Face's squadmates had his whole speech playing over the ship's intercoms, allowing the entire crew to applaud.
  Face: Thank you, thank you. Performances every hour, on the hour. Imperial madmen a speciality.

Live-Action TV

• Played with on Agents of S.H.I.E.L.D. during Season 7's time travel arc. Simmons and Coulson infiltrate a secure base in the 1950s by having Simmons pretend to be Peggy Carter. They actually have everyone fooled... until Daniel Sousa, who actually knew Carter personally, shows up.
• In the Being Human (UK) episode "The War Child", Eve is being smuggled into a concentration camp by a freedom fighter claiming to be her father. Unfortunately, Mr. Snow tests this story by asking the man what colour Eve's eyes are. He doesn't know.
• Burn Notice: Deals with this on a regular basis, given how many different cover identities the protagonists adopt. In an early episode, Mike pretends to know a friend of the episode villain from prison and is asked if he still makes his famous prison wine. Mike correctly guesses that the villain is trying to Bluff the Imposter, and insists that the acquaintance doesn't drink (which sells his cover).
  • In other episodes, Mike describes what to do when such an anomaly is found: keep lying^*"Some spies, when their cover looks like it's going to be blown, will drop the pretense and retreat. Good spies will lie harder.". In another, similar case, he guesses that the friend doesn't drink, and turns out to have guessed wrong. When the target calls him on it, Mike claims that the guy found religion in prison and quit drinking, which the target accepts.
• In the pilot episode of Cheers, Sam isn't fooled by a teenager's fake ID, because it not only claims he's over forty, it's a falsified military ID.
• Cobra Kai: Early in season 5, to gather information on Terry Silver, Chozen goes undercover in Cobra Kai by posing as a sensei from Kyoto. Unfortunately, Silver is very versed in Japanese culture, and ends up figuring out that Chozen is an imposter when he uses Okinawan mannerisms while toasting him.
  Terry Silver: It seems you weren't entirely honest with me, were you, Chozen?
  Chozen: How did you know?
  Terry Silver: Have you ever heard of a man, Masataka Taketsuru? About a hundred years ago, he moved from Hiroshima to Scotland. He studied organic chemistry. Then he returned to Japan with the secret of great whiskey. He built up his own distillery just outside of Kyoto. His brand, Suntory, the whiskey we drank last night, considered the best in the world. I've had the pleasure of drinking it right where it's made. And every time I raise a glass with one of my old friends from Kyoto, we toast "kanpai". So imagine my surprise when my new friend from Kyoto raises a glass, and says something they would only say in Okinawa.
  Chozen: [realizes] "Karii".
  Terry Silver: "Karii".
• Played for Laughs in an episode of Criminal Minds, when JJ, Emily, and Penelope are out at a bar and Emily is hit on by Brad--a Real FBI Agent. She brings him back to their table and introduces him, and the girls proceed to play dumb, asking him all sorts of questions about his work and what it's like at "Kwan-ti-co." Brad talks like a regular 007, but unfortunately, most of his work is "classified." Including his badge, when the girls ask to see it. Then they pull the rug out from underneath him and it's gloriously funny.
  Emily: Tell me, Brad, does it look anything like this? (displays her own FBI badge)
  JJ: Or...this? (shows her badge)
  Penelope: Or maybe this? (shows her badge)
  Brad: (wordlessly escapes this situation as quickly as possible)
• Death in Paradise: In "Death of a Detective", a woman has assumed the identity of her sister. However, she had never read the novel on which her sister did her dissertation at Cambridge.
• One episode of Degrassi Junior High has Snake trying to get alcohol for a party. It would all be well and good except for the fact that the fake ID doesn't even have a picture on it.
• Doctor Who:
  • In "The Time Warrior", while helping UNIT with a case of suddenly missing scientists, the Doctor runs into a young scientist by the name of Smith. The Doctor praises her on that virology paper she published, especially since given her age she would've had to have written it when she was five. At which point Sarah Jane Smith admits she's not really a scientist (that's her aunt, who's away in America), just a journalist.
  • In "Nightmare of Eden", the Fourth Doctor claims to Captain Rigg that he's an agent of Galactic Salvage Insurance, only for the captain to point out Galactic Salvage has been out of business for twenty years. Being the Doctor, he makes a brazen attempt to keep the bluff going:
    The Doctor: I wondered why I hadn't been paid.
    Rigg: That's not good enough.
    The Doctor: That's what I said!
  • The addition of the Doctor's psychic paper gives some interesting variations on the trope. In particular, the Eleventh Doctor once tried to claim he was universally recognized as a mature and responsible adult, to which the psychic paper revolts. It was a lie too big.
  • In "Family of Blood", the Doctor did put some effort into his disguise as John Smith, so if people asked about his past he could tell them... but once Joan Redfern gets suspicious, she points out the details given are just dry facts. He can say where he grew up, but can't give any personal details, like where he played as a child.
• Subverted in the Farscape episode "Losing Time". The crew are informed that an "energy rider" had invaded the body of one of them and that they can find out who it is since the rider won't know "details of the heart" like family members. They get misdirected when a new member of the crew tells a different story about her background than the one she initially told them and they assume she's lying. In truth, she'd been lying the first time.
• Game of Thrones. Brienne is escorting Jaime Lannister back to King's Landing when three Northern soldiers recognise him as the notorious Kingslayer. Naturally they deny it, with Brienne claiming Jaime is a thief she is taking to Riverrun to be thrown in the dungeons.
  Soldier: I've a question for you both, and I want you both to answer it at the same time. I count to three, you both answer. What's his name? One... two... three...
  [Brienne and Jaime exchange a Meaningful Look, then she kills all three soldiers]
• The Good Guys: One of the explosive smugglers from "Cop Killer" recently learned how to fix air conditioners in prison. During a Janitor Impersonation Infiltration, he uses this knowledge to correctly answer a test question from the suspicious Samantha.
• Graceland:
  • Narrowly averted in the pilot. Mike has to go undercover as the brother-in-law of a low-level drug dealer in order to prevent Russian mobsters from killing the dealer's family. The brother-in-law is a real person with a criminal record that the Russians are aware of. Mike only vaguely matches the man's description and is shorter and thinner than him. They compensate by having him wear platform shoes and blaming the weight loss on drug use. Mike still almost gets caught when he has to tell the Russians about a murder he claims to have committed and the FBI agents listening in on the conversation from Mission Control have to quickly create a fake crime report that matches what Mike said and insert it into the relevant police databases.
  • In another episode Mike pre-empts this when he pretends to be a Marine selling stolen military weapons. Almost immediately after selling the weapons to a gang, the gang gets hijacked by another gang that takes those weapons. When the angry gang leader suspects a setup and questions Mike about his whereabouts during this hijack, Mike angrily tells them that he was on base and they can easily verify it by checking with his duty sergeant. The sergeant does not exist but Mike knows that, unlike the Russian mobsters, these gang bangers do not have the contacts to verify his story or even confirm that someone with that name is even enlisted in the Marine Corps.
• On Hawaii Five-0, Grover finds himself and his family threatened by an old mobster foe. An old FBI pal of Grover's gets them to a smaller island, introducing a pair of agents from the local field office who will take them to a safehouse. But halfway down the road, Grover suddenly spins the car around to take off. He tells his wife the "agents" don't look as if they've set foot in Hawaii in their lives with no tan lines of any sort. That means they're from the mob and Grover's "friend" set them up.
• Showed up on occasion in Leverage. In one instance; Sophie, the grifter, needs to use a cover identity as a private security advisor initially developed for Elliot, the hitter. When the security guard checking her fake ID does a double take at the inconsistencies; Sophie distracts him by suckerpunching another guard and berating them for their supposed lack of preparation.
• Masters of the Air: In Part 4, the Belgian Resistance interrogates several downed American Airmen to see if any of them are genuine or a German infiltrator. The interrogator becomes suspicious of one of them when he writes the current date the European day-month-year style rather than the American month-day-year style, and when he has him sing the American National Anthem, where he sings it with pure confidence even when flubbing a line (whereas the two genuine American airmen nervously try to remember the lyrics as they sing it). Later, when one of the Belgians asks the supposed airman for a light, the lighter he pulls out is not an American "Zippo" lighter ubiquitous to the US Military but rather an Austrian Model, something no American would realistically have access to, much less have on hand, thus giving him away. The moment they see this, they shoot the infiltrator on the spot.
• Midsomer Murders:
  • In "Orchis Fatalis", infamous orchid smuggler Jimmy Fong initially pretends to be a Chinese takeaway delivery driver so as to be Beneath Notice while he goes about his business, even adopting Elective Broken Language. Barnaby isn't fooled because despite these touches, Fong's still driving a flashy car far above the salary of a delivery driver.
  • In "The Stitcher's Society", a Private Investigator joins the eponymous society: a support group for survivors of heart surgery. However, as he has never had heart surgery, he lacks the distinctive 'zipper' scar down the centre of his chest. This ends badly for him when the killer sees him without a shirt and realises that he is an imposter and must have an ulterior motive for being there.
• Motive: In "The Vanishing Policeman", the murderer is posing as a police officer in order to stage a fake suicide. However, in watching video of the 'suicide', Angie notices that he was wearing his baton on his right side. Angie knew that the officer in question had been wounded the week before and, as the baton rubbed against his stitches, he had moved it from the right-hand side of his belt to the left.
• The first season finale of Mr. & Mrs. Smith (2024) has John and Jane, a pair of government assassins, having been tracked and surveilled by an agent of...Southbey's. It turns out that while their covers can fool any law enforcement agency, real estate firms know something is seriously wrong about two "software engineers" being able to afford a Manhattan brownstone with garage and pool worth at least $2.5 million. That they were able to make expansions without any records of permits or even a city inspector report was another red flag.
• This almost gets Callen killed in an episode of NCIS: Los Angeles. The team intercepts the communications of a terrorist cell and realize that the terrorists are expecting a new member to arrive whom they have apparently never met before. They arrest the terrorist and Callen takes his place. However, the cell's leader actually went to school with the man Callen is impersonating. They were very young at the time and never became friends so Callen is able to bluff his way through the questions he is asked. However, he trips himself up because, in their hurry to make the switch, the team failed to realize that the new terrorist is left-handed. The cell leader clearly remembered this about his former schoolmate and when he sees Callen write using his right hand, he knows that they are being tricked.
• Person of Interest:
  • An executive at a computer security company tries to send flowers to the parents of an employee killed in a traffic accident. When it turns out that the parents do not exist, she quickly realizes that the man was a Chinese spy. She also realizes that someone high up in the company must have been working with the spy or this would have come up on a routine background check. It turns out that many of the company's employees, including most of the executives, were Chinese spies.
  • The Machine has Root and Shaw infiltrate a CIA black site by having them pretend that Shaw is a CIA agent delivering Root as a prisoner. The Machine is unable to obtain all the correct security codes so Shaw has to say that she was in a hurry and forgot to get the new codes. The suspicious guard is about to radio in to his superiors for verification of her identity but his radio malfunctions. Shaw is able to tell him the correct procedure for resetting the radio. The procedure was designed specifically to prevent unauthorized personnel from using the black site's equipment so the guard accepts this as proof that Shaw really is part of the unit.
  • Reese is captured along with three other Badass in a Nice Suit mercenaries in "Prisoner's Dilemma". All have impeccable cover identities, but FBI agent Donnelly is convinced one is the Man in the Suit vigilante, so it becomes a race to maintain Reese's cover until one of the mercenaries' cracks.
  • In Season 4, Reese has a cover identity as a police detective. While working as a tactical instructor, a female trainee notes that he uses military tactics despite his file not showing the appropriate background. Reese fudges the issue by claiming he was taught by an instructor who was a Gulf War veteran.
• The Saint: In "The Organisation Man", Templar, working undercover for British military intelligence, has infiltrated a small private army whose current assignment is to liberate a captured, high-profile spy. They're disguised in the stolen tartans of a detachment of Scottish soldiers who were due to take over guard duty, and on handover, are being inspected by the current guard commander. Their disguises are perfect (as befits a regiment known for their punctilious attention to detail), up until the point when the commander notices that they've all placed their sgian-dubh knives in the wrong sock - the right rather than the left.
• The British comedy series Spaced features Tim and Daisy, who are pretending to be a couple in order to rent an apartment. Though they attempt to be as thorough as possible by learning a multitude of mundane details about each other ("I forgot what you got for your fifth birthday!" "Miniature drum kit"), they get caught in their lie while fumbling around regarding what day they had sex first vs. what day they kissed first. A much worse mistake is barely averted as, just before they go in, they realize they've never learned each other's names.
• Star Trek: The Next Generation:
  • In "Future Imperfect", a boy posing as Riker's son misses a vital piece of information about the woman he claims is his mother — she only ever existed as a hologram. He then slips up again when he refers to Commander Tomalak as "Ambassador", which proved to Riker that the Romulan base was yet another simulation.
  • In "Rightful Heir", the legendary Kahless the Unforgettable makes his prophesized return. Kahless' identity is seemingly proved when he mentions details about his life kept secret by the priesthood and even a DNA test from an ancient artifact is shown to be a match. Chancellor Gowron however is not convinced and notes that Kahless is unable to remember actual details outside of scripture (for example, Kahless tells a well-known parable about a man who refused to take shelter from a storm but couldn't remember the man's name or what he looked like). Finally, Gowron manages to beat Kahless in a fight, which the most legendary warrior in Klingon history should not lose. The priesthood comes clean and confesses to having cloned Kahless and implanted scripture in his memories to take over the Empire.
• Star Trek: Discovery: Pike, Burnham, and Owosekun are undercover on a plant where the human population has regressed to an agrarian, low technology civilization. They pretend to be visitors from another community, but one of the people they meet sees through it because their faces and hands lack the weathered and calloused look of manual laborers.
• On Turn an American agent is trying to infiltrate British-occupied New York by posing as a British officer who was captured by the Americans and is being exchanged in a prisoner swap. The agent is quickly discovered when he does not know his regiment's motto and later makes a few more mistakes including failing basic European dinner etiquette by holding his fork in his left hand.
• An episode of Veronica Mars deals with Veronica's dad, who has been temporarily reinstated as sheriff, cracking down on bars that serve alcohol to minors despite the obviously fake IDs. The only two teens whose IDs are very good Sheriff Mars happens to know personally, and he also happens to know that they were laminated using his own ID card printer. He then has his deputies conduct random ID checks at bars. When that doesn't yield results, he sets up the same two teens with obvious fakes (with pictures of Jon Bon Jovi and Biggie Smalls) and has them drinking non-alcoholic beer at a bar about to be inspected by one of his deputies. When the deputy doesn't attempt to arrest the two teens despite the obvious fakes, the sheriff has him and three others fired.

Radio

• Paul Temple and his wife Steve, in addition to revealing impostors by using a question or comment, have a couple of occasions where an impostor simply gets one detail wrong.
  • In Paul Temple and the Alex Affair, Temple gets a phone call from his friend Leo Brent, whom he has sent to stake out a hotel. The caller is a plausible impostor, but his error is addressing Temple several times as 'Paul', when, as Temple remarks to Steve, Brent always calls him 'Temple'.
  • In one episode, Steve receives a phone call from another very plausible impostor claiming to be her husband. The only way she knows it isn't him is because he uses the expression "By George!" rather than his usual "By Timothy!"

Tabletop Games

• This entire trope is a game mechanic in Demon: The Descent. Long story short: The Player Characters are the titular demons and can create pacts with mortals, which trades some part of the mortal's life (fiancée, house, university education, etc.) for money, power, love, any of the usual stuff, really. The reason Demons do this is so they can integrate whatever the mortal traded away onto their own supernatural disguises to make them more "real", but the catch is only things directly involved in the deal get changed. So the Demon might gain the true love and affection of someone's fiancée, but all of their family will remember them being engaged to a completely different person, or you might gain a diploma with all the paperwork to match, but none of the university lecturer's or anyone in the graduating year will remember them. When these discrepancies start getting noticed they start to wear away at the Demon's disguise, which leaves them vulnerable to being noticed by other supernatural creatures, or worse, the God Machine.
• This is a suggested possibility for Shadowrun characters whose false identities fail security scans. On a critical glitch, a suggestion is that some part of the data is clearly false (e.g. an elf's SIN identifies him as a female troll).

Theatre

• The Music Man: "Professor" Harold Hill is a conman that preys on unsuspecting towns, promising to start boys' bands and then skipping town after taking payments for uniforms and instruments. As he's introducing himself Rock Ridge, he says he graduated from the Gary Conservatory in Gary, Indiana in 1905. However, Marian Paroo, the local librarian, privately faces him and tells him that she's figured out that he's a conman by the fact that Gary, IN wasn't established till 1906 (the musical takes place in 1912).

Video Games

• Renard Vulpes in Aviary Attorney goes by Juan Querido, prince of Spain. Problem is that's actually pretty easy to check — there are no significant princes of Spain at the time and "Querido" is probably not a real name. If Falcon tries to bring it up at the trial, instead of a dramatic turnabout, Cocorico and the jury simply say they knew all along and thought it was too obvious to mention.
• In Fallout 2, if you buy the forged citizenship papers for Vault City, the first time you go through the security checkpoint they take an awfully long time scanning them but as long as you keep your cool they'll let you through. If you panic, you'll get caught.
• In Final Fantasy VII the second Reactor bombing mission gets off to a bad start because of this. Avalanche had been using fake IDs to bypass Shinra security checks on the Midgar Railway system, and never had any problems before. This time however, one of the IDs fails the check, and the team is forced to bail from the still moving train. Talking with Jessie a little later reveals it was Cloud's ID that had set off the alarms; she'd tried to "make it special" for him, and whatever that was had been caught by the scanners.
• In a mission in Hitman 2: Silent Assassin, Agent 47 can adopt a disguise of a "Lord Sinclair" to get close to his target (a female doctor). If she asks 47 for the name of "his" wife, though, he won't know what to say before eventually randomly coming up with "Elsie" (which is way off the mark), blowing his cover.
  • Subverted in the 2016 Hitman, where in the Bangkok level 47 can disguise himself as a drummer of his target's band. If he's asked to show off his skills, 47 plays a decent beat and his disguise remains intact.
• One mission in MechAssault has the player pilot a captured enemy Thor into a Word of Blake base to download some intel from their computers. The disguise almost works, until one of the Blake officers asks you to transmit your ID code or be fired upon. Fortunately, they wait just long enough for Foster to download the intel.
• In Saints Row: The Third, the Boss disguises himself as Cyrus Temple, the leader of S.T.A.G., to infiltrate their base and save Shaundi. While Magic Plastic Surgery means the looks and voice are perfect, the Boss makes little to no attempt to try and speak like Cyrus. Depending on your chosen voice and gender, this can result in "Cyrus" doing things like hitting on his subordinate, talking about how cute a guy is, speaking in various accents, or growling like a zombie.
  Kia: Welcome back, sir.
  Cyrus-Boss: Whassup?
• Papers, Please: Spotting these is the core gameplay element of the game.
• Professor Layton:
  • Professor Layton and the Curious Village: Layton finds a newspaper which shows Inspector Chelmey enjoying his wife's cakes, despite him previously rejecting Matthew's sweets. When Layton confronts him, he also deliberately says Chelmey's wife's wrong name, thus the inspector reveals himself to be Don Paolo in disguise.
  • Professor Layton and the Unwound Future: When Don Paolo is impersonating Dean Delmona in the future, he pretends to have aged by wearing a white toupee instead of a brown one. Turns out the real dean wears a brown toupee, thus allowing Layton to identify him as an imposter.
• In Tales of Symphonia, Raine begins to question Kratos' identity more and more as the game goes on, and even begins to openly challenge it. He knows way too much about the old world, the Desians, the Church of Martel, angelic language, and on a couple moments even knows more about Raine on such topics, which is way more than a simple mercenary for hire should ever know. Though she never suspected he knew these things because he was thousands of years old and in-league with the Big Bad who rules the world as their God.
• In Tales of Symphonia: Dawn of the New World: Emil Castagnier. Being the summon spirit Ratatosk in human form, Emil lacks a lot of information that would be expected from a resident of Palmacosta - fishing, the Desian Human Ranch nearby, etc. Subverted in that he is unaware of what he is Beneath the Mask for most of the game
• In Team Fortress 2, the Spy has a couple of these built in, even disregarding the spies who are just bad actors. A disguised Spy can't benefit from class-specific special abilities, so most players quickly learn to beware of too-slow Scouts, burning Pyros, and Medics with no ubercharge, along with teammates who aren't Friendly Fireproof.
• One recurring sidequest in Yakuza 0 has you interviewing prospective employees for your real estate company. If you're sharp, you'll notice that one person gives an answer that contradicts something they previously stated. A woman who says she worked for many years at a traditional Japanese inn says she's a great cook—but the dishes she can cook are all Western foods, like spaghetti or meatloaf.

Visual Novels

• In Phoenix Wright: Ace Attorney – Trials and Tribulations, an impersonator doesn't know that the person he's imitating recently suffered an injury that made him unable to hear out of his left ear. When a witness who was fooled by the imitation testifies that the person was wearing an earpiece in his left ear, Phoenix has to point out that it makes no sense.

Webcomics

• In League of Super Redundant Heroes, an alien named Zoolkor Lizard-Face Humankiller has what seems to be the perfect disguise for infiltrating human society, but the name she uses as such, well, needs work.
• In Survivor: Fan Characters, Bonnie returns in one season disguised as "Sarah", a seemingly sweet therapist for "Bonnie" who's actually an actress hired to impersonate her. She invents a sob story as Sarah about a dead mother, which comes back to bite her in the rear end when she's unable to tell Brandi the name of her supposed dead mother.
• In Trapped, Leo kidnaps Chae-ah and shapeshifts into Yunsu to ask where he told her Grimm was hiding. Yunsu never told Chae-ah this information, so she immediately sees through the disguise. Leo then tries to trap Yunsu by shapeshifting into Chae-ah, but Yunsu figures out what's wrong when "Chae-ah" reciprocates his hug.

Web Original

• Big D in Hunter: The Parenting had the ID of a Kevin Wettsworth when he was taken into police custody, and used Kevin's name instead of his own (whatever it is). Big D does pretty well until the cop mentions a Kaitlyn Wettsworth, whom Big D assumes to be Kevin's mother. Kaitlyn is his sister. The cop later remarks that he should have noticed that Big D looks nothing like Kevin's license.
  Cop: Honestly, I mostly thought it odd how you turned from the small, bleak British man on your license into a giant middle-eastern meat slab. It read like an online ad, and it distracted me for the whole interview.
• Not Always Right:
  • Meanwhile, a youngster trying to buy cigarettes is using her older sister's ID, so she looks like the photo and knows all the facts... but the shop clerk went to high school with said sister.
  • The same source had a bouncer ask a guest:
    Bouncer: Is this your ID?
    Guest: Yep.
    Bouncer: [turns to guest's friend] What's her name?
    Friend: Uhhhhh....

Western Animation

• Avatar: The Last Airbender has Sokka trying to pass himself and his sister Katara off as Aang's parents when he gets in trouble with his teacher at a Fire Nation school^note  Trust us, It Makes Sense in Context, it really does, leading to the hilariously badass Paper-Thin Disguise identify of Fire. WANG Fire! And his wife, Sapphire Fire. As with many examples of Refuge in Audacity on the show, this works beyond any reasonable expectation because it's funny.
• This has happened many times to Bugs Bunny, usually with his ears or tail sticking out from his disguise.
• This has also happened, most likely as a Shout-Out to the above, in the Tiny Toon Adventures episode "The Looney Beginning" when Montana Max sees Buster and Babs' tails poking out of their outfits.
• In the My Little Pony: Friendship Is Magic episode "Spike At Your Service", the main characters stage a fake Timberwolf attack for Spike to rescue Applejack from, and Spike is fooled at first until he notices that the fake Timberwolf doesn't have bad breath.
• The Simpsons:
  • In "Blood Feud", Homer attempts to pretend he's Mr. Burns...except he doesn't know what Mr. Burns's first name is^note His full name is Charles Montgomery Burns, and he generally goes by his middle name when asked..
  • In the "Treehouse of Horror X" story "Life's a Glitch, Then You Die", when Homer pretended to be the pianist from the movie Shine. When asked for his name, he responds "Shiny McShine".
  • In "Lard of the Dance", when attempting to steal Springfield Elementary's grease, Homer and Bart are confronted by Groundskeeper Willy. When Willy demands to know what is going on, Homer claims to be a foreign exchange student from Scotland. When Willy presses him for where in Scotland, Homer hesitantly states "North...Kiltown?" When Willy says that he's from North Kilttown and asks if he knows Angus McLeod, Homer inverts the situation, stating there is no Angus McLeod in North Kiltown and it is Willy falsifying his identity.
• Star Wars Resistance: Although Kazuda Xiono uses his real name when he's sent on a spying mission to the Colossus refuelling station, his cover is that he's a mechanic and aspiring pilot. He's fine at the piloting part of it since he used to be an X-Wing pilot in the New Republic Navy, but the mechanical end not so much. Since he spends more time at his mechanic job than flying in the races held at the station, this causes him some trouble and makes his Locked Out of the Loop co-worker Tam Ryvora very suspicious. However, over time, Kaz's mechanical skills improve somewhat.

Real Life

• This is the point of "Security Questions" on websites when you need to reset your password. They're intended to foil someone pretending to be you, by asking questions that only you should know the answer to. Some places invert this and actually advise you to put something that is completely wrong (but that nobody would guess) as the answer, for example if the question is "What is your birthday?" put "Puppy", so that if the pretender does find out your info they can't get into your accounts. (This assumes, of course, that the system will accept such an answer to that particular question; for a system that accepts only dates for a "birthday" question, one can still enter a wrong date.)
• Standard tradecraft for spies when communicating is, to give a hint to their controllers if someone was faking their communications, to have a subtle challenge code that, assuming the spy hadn't gone full Double Agent, would be something the faker wouldn't be able to respond correctly to or even realize they were expected to respond to. The same principle was used for dead-drops: often a legitimate drop required some subtle thing at another location to verify the drop.
• One quick check used in stores to challenge customers who appear too young for the purchase (typically alcohol and/or cigarettes) and might have a fake ID is to ask what year they were born. Someone faking their age is likely to trip up and give their actual birth year or obviously have to stop and think about what year they would have had to have been born to be legal.
• A similar practice works (less reliably) for signature forgers. While the person is signing their name, if they're asked a question that they have to stop and think about, they're more likely to mess up their signature if they're not used to writing it.
• An OSS training film on undercover operations notes the importance of even minor details conforming to an agent's cover story, from clothing appropriate to a person of the agent's supposed means, a haircut that conforms to local trends, all the way down to the presence or absence of callouses on the hands of a laborer vs. an office worker. One section even tells the stories of three agents whose covers were blown by seemingly innocuous details - one who tried to pay for a drink with out-of-date currency, another who didn't pick up on local slang despite supposedly being a local, and a third who was caught wearing hair gel that he could only have purchased in an enemy country. (The complete film is viewable here.)
• Operation Lena, a 1940 attempt to land German spies in Britain, was a laughable and almost immediate failure because of these - although it's also possible that it was intended to fail from the first, as Admiral Canaris, in charge of the Abwehr^note German Military Intelligence, was by this point acting in clandestine opposition to the Nazi government. One of the spies was caught because he walked into a pub and asked for a pint of cider at 9 in the morning^note well outside the restricted window for alcohol sales brought in as part of rationing. Two were found because they were cycling on the wrong side of the road, and also carrying German sausages and hand cream. One was caught because he spoke no English at all! Of the dozen of them, the one who allegedly spoke the best English described their mission as being to find out "How the people are living, how many soldiers there are, and all the things."
• Famously, during the Battle of the Bulge in WWII, the Germans sent English-speaking soldiers dressed as Americans to mess with communications and misdirect reinforcements. U.S. soldiers responded by asking questions such as "Who won the World Series?" that Germans wouldn't know. Though this did lead to at least one incident where it turned out the soldier asking didn't know the right answer, resulting in General Omar Bradley being detained by an MP after being asked what the state capital of Illinois was. Bradley correctly answered Springfield, but the MP mistakenly believed that Chicago was the capital. ^note  There was also a Americanophile German spy who was only picked up by not knowing that Pennsylvania is a Commonwealth. Interestingly, he was not shot as a spy, but was treated as a normal POW - it has been reported that the Americans were so in awe of his American knowledge that the powers that be decided to let him live - and later in life emigrated to America - settling in Harrisburg, Pennsylvania!

• One of the ways Prisoners of War in Vietnam communicated was the 5x5 tap code, where the letter K was substituted with C to turn the alphabet into a grid. One then one taps meant "A", two then one meant "F", and so on. The way that the prisoners ensured that the person they were communicating with was another POW and not a guard was by starting by tapping "Shave and a Haircut", and expecting "Two bits" tapped in return. For some reason, the VC guards could not/would not return the proper response.
• There's a story of a spy who for some reason crossdressed (being a man pretending to be woman) and apparently did quite a good job until a ball was thrown their way and instead of spreading the legs apart (to stretch the skirt and aid in catching) the agent instinctively moved the legs together (to protect, well, yaknow). Apparently that was enough to arouse suspicion and blow the cover of the agent in those more sexist days.
• The entire premise of Stolen Valour spotting more or less relies on this, where people will identify someone masquerading as a soldier or marine by picking out minute details they got wrong in the uniform. For example, Canada's most brazen phony vet "Sergeant" Franck Gervais of Cantley Quebec, who went so far as to dress in his DEUs not only on Remembrance Day and not only to his own wedding, but even had the gall to speak on live TV about his non-existent experiences in the armed forces, was called out owing to a multitude of wrong details on his uniform such as his beret (he wore a maroon beret reserved only for paratroopers who were active jumpers), facial hair (this was before beards were allowed barring a chit or religious exemption, and his wasn't trimmed properly), missing sash (he claimed to be a senior NCO, but wasn't wearing a red sash), and one of his medals (he wore the Medal of Bravery, an extremely rare award being the third-highest honor given to Canadian military). He was called out almost immediately by actual members of the armed forces and charged.

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