[[quoteright:328: [[Manga/GunslingerGirl http://static.tvtropes.org/pmwiki/pub/images/Left_Gun_Behind_2935.jpg]]]]
[[caption-width-right:328:Oops!]]

A character rushes out of the room and a closeup shot reveals they've left their firearm behind, or some other crucial item like a [[CellPhonesAreUseless mobile phone]] or the AmuletOfDependency. Naturally they're going to need that item for the very situation they're about to head into. Bonus points for an OhCrap.

Not related to LeaveBehindAPistol. See also WeHaveForgottenThePhlebotinum.
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!!Examples:

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[[folder: Anime and Manga ]]

* ''GunslingerGirl''. Cyborg girl Triela runs away in tears after realising her handler went on an assassination mission without her and [[SecretStabWound got wounded in the process]]. She leaves both her pistol and conditioning medicine behind, and withdrawal symptoms make her too weak to defend herself when she gets grabbed by a couple of Camorra thugs.

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[[folder: Film ]]

* Invoked in ''{{Film/Sherlock Holmes}}''. Watson is furious when Sherlock leaves without his revolver, knowing [[BatmanGambit he did it deliberately]] so his friend will feel obliged to chase after him.
* ''TheSureThing''. When Gib and Allison leave the hotel room, Allison accidentally leaves her all-important planner (which contains all her money) behind.
* ''Film/PulpFiction''. Vincent is waiting at Butch's apartment to kill him if he shows up. While waiting, Vincent needs to go to the bathroom, so he leaves his Ingram MAC-10 on the kitchen counter. While he's in the bathroom, Butch shows up, and uses the Ingram to kill the unarmed Vincent as he leaves the bathroom.
* While on the way to fire off the flares needed to destroy the titular giant spider in ''TheGiantSpiderInvasion'', Dr. Vance forgets the flares and needs to run back to the car and get them. [[MST3K Mike and the Bots]] immediately call out how dumb this was, since it doesn't add any real tension and only pads out an extra 10 seconds or so of running time.
* In the ''{{ComicBook/Asterix}}'' animated movie ''Asterix Vs Caeser'', Asterix has an argument with his best friend [[TheBigGuy Obelix]] while attending a bath-house in Rome. He storms out while getting dressed, leaving his bottle of [[SuperSerum magic potion]] behind accidently. He does not realise this until he is accosted by two Roman legionnaires, who promptly throw him in jail.
* In ''CrocodileDundee'', the titular character left his [[KnifeNut knife]] behind in the limousine just before he encountered a pimp he'd earlier decked. As things turned ugly, he reached for it to find it no longer there, and only escaped being killed due to timely intervention by the limo driver.

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[[folder: Literature ]]

* The non-fiction book by Creator/DavidSimon, ''Homicide: A Year on the Killing Streets'' mentions that detectives have to remind themselves to take their guns with them, as real life officer-involved shootings are a rare event.
* Subverted in ''TheSilenceOfTheLambs''. When Clarice Starling goes to see Dr. Lecter in Tennessee, she has to turn over her spare reloader for her revolver. When she's discovered and rushed out, she leaves her reloader behind. If you noticed this and were GenreSavvy, then during her final confrontation with Buffalo Bill, you were expecting her to run low (or out) of bullets, look for her reloader and not find it, and have to defeat Buffalo Bill with just OneBulletLeft or an empty gun. In fact, she finishes off Buffalo Bill with several shots and then reloads.
* Slightly different example in ASongOfIceAndFire. While a group of people are escaping from [[spoiler: Ramsay Bolton]], with a plan that requires them to climb down the castle wall with a rope, they get discovered, and one of them decides to pull a HeroicSacrifice YouShallNotPass on the guards chasing them to let the others escape. They go ahead and reach the top of the wall...[[OhCrap only to realise that the person who stayed behind had the rope.]] Despite one of them bursting into hysterical laughter at the absurdity of it, this is ''very'' much PlayedForDrama.
* Played with in ''Literature/MostlyHarmless''. Tricia Macmillian laments her boring life because a few years back she had the opportunity to go with a guy who was from another planet, but right after she went back for her bag, Zaphod left in his spaceship. She then used the mantra "Never go back for your bag." At the present time, she's running late for an interview as a prestigious anchor for a news program, and when she realizes she left her bag upstairs, doesn't bother to get it, citing her mantra. Later, she returns to her hotel room feeling horrible, having completely blown the interview, and goes straight for her bag, which has her contact lenses inside (without which made it impossible for her to read the teleprompter.)
--> "As she dabbed each tiny plastic cup into her eyes, she reflected that if there was one thing life had taught her, it was that there are some times in which you do not go back for your bag and other times when you do. It had yet to teach her to distinguish between the two types of occasions."

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[[folder: Live Action TV ]]

* ''{{Series/Ultraviolet}}''. The protagonist rushes out to meet his [[AllLoveIsUnrequited Unrequited]] LoveInterest, taking his pistol but forgetting the video camera attachment used to identify vampires. This causes problems when he starts suspecting she's a vampire, but has no means of verifying it.
* In the French-German mini-series ''Carlos'', several French detectives go to question a "Peruvian playboy" photographed with a terrorist courier they've picked up for questioning. One detective goes to get his gun, but his commander tells him not to worry as it's just a routine checkup. Unfortunately the so-called playboy turns out to be the terrorist Carlos the Jackal.
* In the last episode of BlackadderTheThird, Prince George is shot dead by the Duke of Wellington after a complicated switcheroo to avoid the prince being shot dead by Wellington. Moments later, the prince reveals that the bullet struck a cigarillo case he was holding over his heart, stopping the bullet. He then finds out that he left the case on his dresser, [[PuffOfLogic and promptly drops back dead]].

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[[folder: Video Games ]]

* ''VideoGame/ParasiteEve'' has Aya go to confront the final boss right before another character would have given her the one weapon that could kill it. Since this character had a habit of giving Aya useless items there was no way for her to know that this one time, it was important.
* ''ShadowRun'' on the Sega Genesis has a double dose of this. The first quest in the game is to scrape together 250 nuyen so you can get your brother Michael's stuff out of storage - it may hold some clues as to why Michael was killed in a firefight. Once you get his stuff, you not only find a credstick for 500 nuyen, but also a Doc Wagon wrist band, which summons immediate medical aid once the user's vitals drop to dangerous levels (like during firefights.)

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[[folder: Western Animation ]]

* One of the Treehouse of Horror specials of ''TheSimpsons'' had a ''Franchise/ANightmareOnElmStreet'' spoof with Groundskeeper Willie as Freddy Krueger. After the Simpsons kids kill the evil Willie in their dreams, they go outside and an alive and well Willie gets off a passing bus and approaches them menacingly -- only to start chasing after the bus because he says he left his gun on it.
* On ''WesternAnimation/TheBoondocks'', the Freeman family goes to the movies and Huey brings along nunchucks because he expects it to be a disaster. Later on he runs into the ushers while on his way to destroy the movie, and he realizes that he left his nunchucks on the sink after using the bathroom.
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