Chekhov's Boomerang

An item gets used. You relax a bit, maybe admire the way it fits into the plot if it's done well. But then, when you were least expecting it, its gets used again. Thanks to The Law of Conservation of Detail, you had put the item out of your mind because it had served its purpose - but what you didn't realize was that it wasn't a single-shot Chekhov's Gun and is actually coming back.

Particularly common in Adventure Games, where a particular item, setting or character might get used three or four times. While this is a good thing in principle, being more realistic, leading to fewer loose ends and going some way to countering Stupidity Is the Only Option, it can throw newbies to the genre who might get stuck on a puzzle for hours because they didn't realise that they'd had an item all the time, they'd just forgotten about it. Of course, this cuts both ways: you might try out something that worked before, but this time it doesn't.

Compare Brick Joke (the gun is dismissed and forgotten before it's used even once, and then comes back). The player may have to apply Chekhov's Boomerang in video games for Final Exam Bosses.

Anime and Manga

 * In Heroman Joey activates ..
 * Fullmetal Alchemist, simply put, does not have throwaway characters. Characters thought to be one time bits will show up in given time. Corpses long forgotten will re-emerge.
 * Well, not completely true: There were a few characters in the first anime that never appeared again, but they were just in Filler episodes. And even then, some of them still have a (slight) impact on the plot.
 * Even in the second anime, based more closely off the manga. You can safely ignore Isaac Mcdougall, the filler character made just for this anime and the subject of the one filler episode, at the end of which he dies, right? There's no way his crazy OC plot will come back in later episodes, right? Wrong.
 * Remember Kimbley? Guy who blows stuff up, saves Ed once, yada-yada? Well, he's dead and absorbed, so now we don't have to see him ever agai- . And that is without mentioning his Philosopher's Stone.
 * Remember Havoc's girlfriend? He was finally going to have a great relationship, but then Mustang makes him dump her. Well, that was pretty funny. She won't be coming back aga-
 * The idea of the exchange with Truth comes back again and again!
 * Neither does the Pokémon Special manga. Bloody hell.
 * On the object end of things, we have with two or more convenient uses after their initial appearance. There are probably more which don't come to mind right now.
 * In xxxHolic and Tsubasa Reservoir Chronicle (a linked story so confusing they use each others guns) notes that a person's true name gives you power over them. Watanuki in the first series gives his name to Yuuko. Later, But then,  Think it's done? Wrong!  Also  However, it is likely that uh... Mugetsu's name is real, at least. Apart from that, who knows?
 * Sanosuke's Zanbattou in Rurouni Kenshin. Just when you thought it was gone for good after his fight with Kenshin,
 * Sanosuke also makes use of this trope a second time in the anime only Shogo Amakusa arc when he unexpectedly gives Shozo the same bombs which he used against Shishio's battleship: Purgatory.
 * Mahou Sensei Negima has one that crosses continuities; an antagonist attacks Negi using an attack that originated in Ken Akamatsu's previous manga Love Hina. There's even Word of God to support the idea that they take place in the same universe.
 * 's involvement in the plot counts as this; after her first appearance, she functions as the Big Bad about a dozen volumes later. Then another dozen or so volumes after that, she becomes plot-important again.
 * Also . He shows up in the Kyoto arc (volumes 4-6), working as a henchman. Fifteen or so volumes later, he makes a reappearance. Turns out
 * Code Geass makes into a Chekhov's Gunman riding a boomerang when Zero Geasses him to "Live!" in order to prevent a Heroic Sacrifice that would have taken the entire Black Knight organization down with him. Later, his Knightmare Frame is armed with a  It activates several other times as well, this is just the most noteworthy one.
 * A number of characters prove to be recurring when we thought they'd only be of the one-shot variety. Most of the characters (the named ones, anyhow) in the series have a series of overlapping relationships, and so show up in multiple contexts. Lady Marianne receives several different interpretations, none of which we were expecting. As well, Nina Einstein starts as a quiet classmate of Lelouch, who then meets Princess Euphemia and develops a crush, who then attempts to build a bomb in the school basement when said crush, who then shows up a year later building the bomb properly, who then sees it used on Tokyo, and then she finally shows up working for Lelouch, building a device that stops the AU-nuke from being used again. Villetta, one of the first characters to be geassed by Lelouch, proves to be one of the most troublesome for him at various key moments.
 * Naruto: is a man who is mentioned to have died off-screen and only seems to have existed to explain . 237 chapters later it turns out that.
 * returns again when
 * On a similar note, another things from that same story arc had it's secret  revealed... only for there to be even more to it even later!.
 * It's also happened with techniques: the Shadow Shuriken technique was used once in the first story arc, but ended up being used again over 350 chapters later when Sasuke is fighting (which was also rigged to split apart sending the pieces everywhere), and then nearly another 50 chapters later, except Naruto was doing with.
 * ? Yeah...
 * Naruto's Rasenshuriken was initially a melee attack, and it also had another drawback in that his hand would take a significant damage while using it. About 100 chapters later, it appears again, but it is now a projectile attack. Although it is not explicitly mentioned, it also has a limitation in that it is wasted if it misses the target or the opponent dodges it. About another 100 chapters later, it appears again and now it is a.
 * Impure World Resurrection has got to be the best example of this in Naruto. It was first used by Orochimaru to revive the first and second Hokages, and it didn't show up again for over three hundred chapters!
 * In the arc where he first appears, Sai refers to a dead brother. This is commented on quite a bit, showing Sai's lack of emotion and artistic ability. Much, much, much later, this turns out to be his Berserk Button, which is pressed by Kabuto in two ways.
 * In the arc where he first appears, Sai refers to a dead brother. This is commented on quite a bit, showing Sai's lack of emotion and artistic ability. Much, much, much later, this turns out to be his Berserk Button, which is pressed by Kabuto in two ways.


 * One Piece does this frequently with some of the Loads and Loads of Characters (like and ) ending up important hundreds of chapters after they were introduced. In fact "Oda never forgets" has become something of a meme among One Piece fandom.
 * Monster - Johann's candy, the story books, Three Frogs, and many others.
 * Pulled off in a massive scale in the last arc of the Desert Punk anime, where half the apparently one-shot characters all show back up.
 * In Yu-Gi-Oh! GX The Phantom Demons/Sacred Beasts cards are the main plot point of Season 1. They're defeated and sealed away. They suddenly become relevant again mid-way through Season 3 when the new villain obtains them and uses them in a single duel. They then disappear again. Towards the end of Season 3, they make another apperance. And then they're never mentioned again, despite having the power to destroy the world.
 * Shortly after the end of her arc we find out that Erza, who we saw in an earlier chapter of Fairy Tail loosing an eye when she was young, got a fake magic eye as a replacement. Because of this she only receives half the blast from a petrification gaze and is easily broken out the spell. After about another arc people forget she ever lost an eye at all, until she uses the fake one to see through an illusion.
 * The Ultra Sacred water (presumably the water from the Garlic Junior arc of Z, and not similarly named waters from Dragon Ball) in Dragon Ball GT, which was useful to get the characters cured from Baby's control.
 * Remember that time way back near the beginning of Magical Girl Lyrical Nanoha where the heroine used a little spell called "Area Search?" Well, in Striker S, it comes back big time.
 * Lancia's Ring in Katekyo Hitman Reborn!. A small gift from Lancia to Tsuna in the end of the Varia Arc, forgetting about it causes Tsuna, Gokudera, and Lal Mirch to be attacked by a Strau Mosca, then be found by . Then, at the very end of the Future Arc,.
 * The Lagann Impact in Gurren Lagann might count: its primary use is to hijack enemy Ganmen which it does successfully nearly all of the time, the only exception being the Lazengann which blew up it's own arm before it could've been taken over. Afterwards, it's completely forgotten... until the final battle where it One Hit Kills the Anti-Spiral.
 * In the animated series of Super Robot Wars Original Generation: The Inspector,
 * Mobile Suit Gundam 00: in episode 19, Tieria utilized the almost secret of his Gundam Virtue - Nadleeh and its Trial System - which control any mobile suit connected to the Veda computer. The Trial System demonstrates its ability to stop the Gundam Thrones dead in their tracks but is disabled by someone hacked into Veda. Never to be seen again, especially not after being disabled ?
 * After realizing Veda might no longer be safe, Celestial Being programs new operating systems for the Gundams so that they can operate independently of Veda (in season one). They also have to fall back on this strategy quickly after speculating on the risk. During the final episode (of season two),
 * In Zero no Tsukaima, Princess Henrietta passed to Louise her mother's ring the "Water Ruby" as a good luck charm after assigning her to a mission in Albion. The ring became vital when it was used to convince Prince Wales of Albion that Louise is really Tristain's ambassador.
 * The first season of Star Blazers / Space Battleship Yamato was fairly episodic in nature, and usually involved the Gamilons trying a particular plan or gizmo against the heroes which would not turn up again. One episode involved a tract of space laced with floating space mines. Another episode had a teleportation device that could make a Gamilon battleship appear out of nowhere. In the second season, long after we'd forgotten about both, Desslok brilliantly combined the two by teleporting a mess of space mines directly in front of the ship's Wave Motion Gun, so they can't fire it without blowing up their own ship. Clever guy, Desslok.

Comic Books

 * In Pre Crisis Superman comics, a minor Silver Age story involved Superman gathering kryptonite from around the world, forming it into a small island in the ocean (there were a lot of kryptonite meteorites in those days!), and then propelling the whole thing into outer space to get rid of it. Still, it was the Silver Age, so kryptonite kept turning up on Earth despite this. Years later, DC Comics decided to stop using kryptonite as an easy plot device, so they had a freak accident destroy all the kryptonite on Earth, and the Superman comics went for a while with no (or at least fewer) stories involving the stuff. Writers missed it though, so years after that, they had the long-forgotten "Superman Island" of kryptonite return from space and scatter the stuff all over the world again.
 * Alan Moore once wrote a story prophesying the end of the Green Lantern Corps. Fast-forward a decade or two, and it's become the basis for the Blackest Night event.
 * Actually used twice. The "Blackest Night" Prophecy was also used in the early 1990's when the Green Lantern Corps was destroyed for the first time, after when Hal Jordan went mad with grief and became Parallax. "Blackest Night" was also the title of one of the comics leading to the end of that same arc, implying that Parallax/Jordan caused the Blackest Night. The Universe has since been rebooted and the prophecy retconned, however, so it's likely that in canon the first occurrence was just a warm-up.
 * The first one didn't include Sodam Yat or Ranxx the Sentient City, both mentioned in the original Alan Moore story.

Film

 * The hoverboard in the Back to The Future sequels. At the end of Part II, Marty uses a hoverboard he brought back from 2015 to get back Gray's Sports Almanac. He uses the hoverboard again at the end of Part III.
 * Lightning being enough to qualify for the 1.21 gigawatts. Obviously important in the first film, then it works again * accidentally* in the second.
 * Bullet-proof vest, too. All three films, actually. Sort of.
 * In the new G.I. Joe film, the tracking device.
 * The ivory pipe in National Treasure. It's almost a Swiss Army MacGuffin.
 * History of the World, Part I: "Only a miracle can save us now!"
 * Big Jim Slade in The Kentucky Fried Movie.
 * Doug's statue-impaled matress in The Hangover.
 * All of the Matt Helm films starring Dean Martin have at least one of these.
 * Despicable Me. Anti-gravity serum + minion. Hilarity Ensues.
 * The character of Bonnie from Toy Story 3 who first plays a part in . She then comes back into play.
 * Jack's compass from Pirates of the Caribbean. It is introduced in the first film as a (presumably broken) compass that doesn't point north, however later in the movie Jack uses it to lead the Interceptor to the Isla de Muerta. It then becomes a sort of MacGuffin in Dead Man's Chest when it is revealed to lead the user to whatever they want most.

Literature

 * In Sandy Mitchell's Warhammer 40,000, Ferik Jurgen, assistant to Commissar Ciaphas Cain, HERO OF THE IMPERIUM!. His unique status as a "blank" makes him impossibly useful and extremely effective, and at the most unusually convenient moments...
 * Let's not forget the good Commissar's skill with a chainsword and las pistol, as well as his "friendly" relationship with a certain Ordo Xenos Inquisitor.
 * After having been completely ignored since the second book, the become the key to the final resolution of the Sword of Truth series.
 * A regular event in the Harry Potter books. One good example is basilisk venom. This is established in the second book to be a deadly and destructive substance. This property comes into play at the end of the book when Harry . Five books later, Harry, Ron, and Hermione are desperate for a way to.
 * On that note,
 * Still about . Now that's what I call a Chekhov's Boomerang!
 * For that matter, Tom Riddle's diary is one as well—when it appeared in the second book it seemed like a mere MacGuffin for Harry to face Voldemort again. After it was destroyed, it seemed to have served its purpose and could be forgotten about like the Philosopher's Stone. And then in sixth book, Dumbledore explains about the Horcruxes and we discover that the diary was a major clue.
 * Dumbledore's Chocolate Frog card is probably the oldest boomerang in Jo's arsenal; Harry reads it on the train to Hogwarts, and uses it about halfway through the book to identify  Nothing else on the card is useful until the very last book, when Dumbledore's duel against Grindelwald is brought up again as an important point.
 * Matthew Reilly often re-uses plot devices. For example, in Scarecrow, Knight revealed he was able to track Gant on his Palm Pilot because he hit her with a cloud of transmitting microdots. He used the same trick to track down Schofield. Mother saw this, and used his Palm Pilot to track down Schofield again.
 * In Terry Pratchett's Nation, Mau leaves an axe in a tree in the opening scene. After a tsunami knocks the tree into the ocean, he paddles past it in a canoe and feels vaguely cheated when he can't pull the axe out. Then, in the final confrontation with the Big Bad, he's unarmed, desperate, and hiding behind a sunken log. Guess which log it turns out to be...
 * There's an enormously potent boomerang thrown at the end of The Hobbit in the shape of Bilbo Baggins' magic ring, which has the handy property of making its wearer invisible - naturally a Chekhov's Gun, as Bilbo is able to take advantage of this fact on a couple of crucial occasions before the end of the story. But then the ring pops up again unexpectedly some years later in The Lord of the Rings.
 * In The Wheel of Time, Callandor. It's the central MacGuffin of the third book, but soon after fulfilling prophecy by drawing it, Rand leaves it behind, and at the end of the fourth book he acquires the Choedan Kal, an even more powerful Amplifier Artifact. Callandor comes back in the eighth book, when he uses it against the Seanchan, but it turns out to be too dangerous to use, so he puts it aside again. Then, over the next few books, it's noted how odd that Callandor is central to the prophecies but the Choedan Kal are not even mentioned,, and it's increasingly clear that Rand must use it in the Last Battle.
 * In Daemon, the Oberstleutenant Boerner bot was used to bring Loki/Gragg into the Daemon's circle around halfway through and isn't mentioned again until some way into the sequel Freedom.
 * In Warrior Cats, the  from Sunset. First,   Then later,

Live Action TV
"Jacob/Selmak: "I have no idea how to alter a Stargate to perform such a function. I don't know of anyone who can." Sam: "I think I know someone.""
 * One of the alternate names for this trope is from Buffy the Vampire Slayer. Olaf's Hammer was a hammer used by Anya's ex-husband, current troll god. It turned out to be the one thing the Scoobies had access to that could kick Hellgod ass.
 * Also, Xander's knowledge from turning into Military Guy came up more than once. Although by the second time, he didn't remember as much.
 * Buffy's rocket launcher turns up five years later for a Funny Background Event.
 * Hercules: The Legendary Journeys introduced the 'Hinds Blood Dagger', which had the power to kill Gods. The dagger served its purpose plot-wise,, and then Hercules  . It later reappears on HTLJ's spin-off Xena: Warrior Princess, and is the object of at least four characters desires over the course of two episodes. It is later used to threaten   and   before being 'disposed of' for good.
 * Some plot elements from Lost might arguably fall into this category (although some fans will probably insist that everything on this show happens for a reason, and everything is planned out in advance). For example, in the season 1 finale, Jack, Kate, Locke and Hurley take several stacks of dynamite from the Black Rock and use some (but not all) of them to blow open the hatch In the season 2 episode "Everybody Hates Hugo", Hurley wants to use the leftover dynamite to blow up, although Rose ultimately manages to change his mind. The dynamite is finally used
 * Crazy to see this dynamite as an example of coming back out of nowhere one season later, given that it was again explored at the END of the series, when Richard planned on blowing up the plane.
 * The Dharma van in Season 3, which was originally the centerpiece of a filler episode. Most of the season went by without it appearing again, until it was shown in a flashback . Then, in the season finale,.
 * Stargate SG-1 and its Spin-Off Stargate Atlantis have very long memories, with many items you'd filed under Forgotten Phlebotinum years ago coming back.
 * A good specific example is the Ancient communication stones: Introduced originally for a humorous clip show episode where a random schmuck finds out about the Stargate program through it, then used a season later to contact the Ori galaxy, and then used again in an Atlantis episode a few years after that.
 * And now it's a fundamental plot device in Universe.
 * Another SG-1 example: the protagonists create a virus that will render a Stargate nonfunctional, and they use it on the Stargate of a planet owned by Ba'al. Demonstrating amazing knowledge of the Stargates' programming, he modifies it to spread throughout the whole Stargate network, shutting down every 'gate in the universe before they manage to reverse the effects. Then, a number of episodes later, they need to get an Ancient super-weapon working to wipe out the Replicators (who threaten to consume all matter in the galaxy), and it comes up that they need to figure out how to dial every Stargate in the galaxy simultaneously.


 * Another is the Quantum Mirror from "There but for the Grace of God" it is used a few seasons later to introduce an alternate universe Carter and Kawalsky (killed of in the beginning of the series) for an episode. It is then referenced in season 9 as a possible solution for a problem they had encountered, but it had been destroyed.
 * The healing machine introduced near the end of Babylon 5's first season, and used 3 episodes later to revive Garibaldi. Then at the very end of the fourth season, someone uses it for a Heroic Sacrifice.
 * In Star Trek: The Next Generation, the Enterprise's use of the deflector as a weapon seemed pretty nifty, even if it didn't work. You didn't expect this to become a standard trick in every subsequent series.
 * The new Doctor Who uses this trope regularly, often to set up a dramatic scene for the season finale by introducing a concept earlier in the season.
 * The two parter "Human Nature"/"Family of Blood" hinges on The Doctor's Time Lord self being concealed in a fob-watch. This reappears a few episodes later in "Utopia."
 * One very persistent boomerang, even banging back and forth between Torchwood and Doctor Who, is the Doctor's severed hand. After having been cut off the Doctor in "The Christmas Invasion," we see it in a jar for the entirety of the first season of Torchwood. At the end of the season it starts pulsating, alerting Jack the Doctor is near. Just the moment you think it has served its purpose, bringing Jack and the Doctor together in "Utopia", the Master steals it along with the TARDIS at the end of the very same episode and then proceeds to use to grab the Doctor's genetic code and age him in "The Sound of Drums" and then even further in "Last of the Time Lords". After the Doctor defeats the Master you think the damn thing is finally done with, but no, it's pointed out to Donna and Martha in "The Doctor's Daughter," and takes the Doctor's regeneration energy after he gets shot and creates a copy of the Doctor that goes on to live with Rose Tyler in "Journey's End".
 * And in series 6, the Teselecta robot, which is controlled by temporarily-miniaturised humans and which can impersonate anyone, has an episode devoted to it. In the series finale, it cameos briefly among several of the Doctor's friends and enemies while he's researching the Silence to find out why he has to die. That's it, right? No!
 * My Name Is Earl: Kenny, the first person Earl made restitution to after creating his list, has been made use of for his computer skills and working at a copy place several times since then. Once he got Earl, Randy, Joy, and Darnell jobs in an office by taking the computer literacy test four times - once for each of them.
 * In one of the first few episodes of NCIS, it is established that Abby is fluent in sign language, since both of her parents are deaf. When she appears in the spinoff series NCIS: Los Angeles, she is kidnapped by a serial killer who streams live video of her online. He also gives her a paralytic that wears off gradually as the episode progresses, starting with her hands. As soon as she is able, she begins fingerspelling to the team, such as the fact that the door is booby-trapped. Luckily there's another signer on the team...
 * Ted from How I Met Your Mother, was established as knowing sign language (to conveniently help/hurt Barney's claim that he was his deaf brother). This casually came up later, when he spoke to his ex's deaf boyfriend.
 * The Eye of Jupiter that turned out to be significant in Season 3 of Battlestar Galactica Reimagined was originally just one of many random pieces of artwork actress Katee Sackhoff had painted on the wall of the set of Starbuck's apartment for the Caprica arc in Season 2. Which is kind of spooky if you think about it...
 * Linkara recently pointed out the Zeo Crystal had been used like this in Mighty Morphin Power Rangers in the transition to Power Rangers Zeo. It was first introduced mid-season as a plot device to drive the conflict between the heroes and villains for a couple of episodes, and, knowing Power Rangers, you would expect it never to be used again, but, at the end of the season/transition between series, it comes back as a way to restore the Power Rangers to their adult forms and give them new powers.
 * Unsurprisingly, Super Sentai has versions of this, since its footage is used for Power Rangers. Nearly every series has had a movie in theaters, and in recent years there has almost always been an exclusive powerup of some sort introduced, either for the rangers, their mecha, and sometimes both. They would then later be remembered by the rangers arbitrarily at some point later in the season and used only once, maybe twice before its end. (Sometimes after its end with the teamup movies) The only series so far with repeated use of the movie powerup in-series is Shinkenger's Kyoryuu Origami Disc.
 * Naturally, when some of these were translated to their respective American seasons, they ended up becoming Forgotten Phlebotinum instead. Though some of these were only used for finale arcs or teamups with explainations why they were unavaiable before, justifying that status.
 * Power Rangers Time Force, has the Electrobooster which is used for its function in the episode it is introduced, and then gets stored in the teams hideout where it comes back to play a part in the All Your Base Are Belong to Us finally.
 * Father Ted uses this as a literal Brick Joke in the episode Speed 3, a ludicrous spoof where Dougal will be blown up if the milk float he's driving goes under 4 mph. After a brainstorming session with other priests proves fruitless, Ted uses Father Jack's pet brick (which he tripped over earlier) to weigh down the accelerator allowing Dougal to escape. After the bomb goes off after colliding with the evil milkman, Ted is knocked out by the brick as it plunges down from the sky. Yes, it's that kind of show.
 * Midway through the Covert Affairs episode "What's the Frequency, Kenneth?", Annie, sneaking into an office at the Smithsonian, notices a trip alarm and doesn't trip it. So you just know she's going to trip it as she sneaks back out, which of course, she does; doors slam shut, the whole works. At the end of the episode, she's running away from the episode's main villain... and leads him right into the same room, wherein he trips the same alarm.

Mythology

 * Older Than Feudalism: An example from Greek Mythology, starting with the Archaic Catalog of Women. A boomerang on several levels: when Heracles (better known by his Roman name, Hercules) slayed the Hydra, he dipped his arrows in its poisonous blood thinking that Someday This Will Come in Handy. He winds up using it to kill a centaur named Nessos who meant to rape his (current) wife, Deianeira. Before he dies, though, the Nessos tells Deianeira to take his blood and use it as a love potion on Heracles, if the need should ever arise. She does so, and when she hears about Heracles' interest in the woman Iole, she anoints his clothes with it. The next morning, as Heracles burned sacrifice to the gods, the heat from the flames caused the Hydra's blood to eat away at his flesh, leading to his death. And then those arrows are used again by Philoctetes to mortally wound Paris during the Trojan War.

Video Games

 * Discworld II: Everything from the pot of glue through the art of beekeeping to the continual theft of stuff from Mrs. Cake's house.
 * The Secret of Monkey Island: The root beer.
 * Monkey Island 2: LeChuck's Revenge: The voodoo doll.
 * The Curse of Monkey Island: The hangover cure and the crowbar.
 * Escape from Monkey Island: The Ultimate Insult, the gold-plated banana picker ("Hey, I get to use this more than once!").
 * Tales of Monkey Island: The Feast for the Senses (In reverse the second time).
 * Rule of thumb: If you're taught how to make one of something, you're gonna need at least two of it.
 * Case in point: You learn how to make a key in Edna and Harvey: The Breakout.
 * Tales has several minor others spread across the chapters: The Pyrite Parrot,, the Eye of the Manatee...
 * The Cane of Pacci in The Legend of Zelda the Minish Cap. You receive it early in the game, it helps for a while, it gets used less and less as you get further into the game and no truly new uses for it appear for quite some time...then all of a sudden, you need it again.
 * Not all that uncommon in the other Zelda games, as the player's inventory can become rather stuffed.
 * One of the more prominent examples is in Twilight Princess. Early in the game, Link, when talking to the mayor before leaving town, has to catch a runaway goat, stopping it in its tracks and throwing it to the side. This later comes into play when Link is climbing Death Mountain (this time, against charging Gorons), and is even required to beat the mid-boss that he battles in the dungeon that follows immediately after climbing said mountain. This skill is pretty much forgotten about for the rest of the game,.
 * In Sonic Adventure 2, the Mystic Melodies seem useless after doing the lost Chao missions, but some Hard Level missions require them for advancement.
 * Also required in one case to get another upgrade. In fact, Security Hall almost seems like an aversion of the "You need the Mystic Melody to get the Lost Chao" rule until you remember that you needed the Mystic Melody to get the Treasure Scope, found in that very level, which was necessary to get the Lost Chao.
 * In Mega Man Star Force, you get 5 cards to summon 5 Navis, each of which are used 3 times: after you get them, in the final area, and in an optional puzzle. Thing is, you may not realize the last one.
 * Then there's the third game with Magnes' rocket. Launching it is the main objective of Echo Ridge Elementary's Science Club, and Luna 4 Prez gets caught up in it to secure votes for Luna. Once it gets launched, players tend to forget about it until the very end - where the same incident that almost caused the rocket to explode gave it the Noise resistance it needs to get close enough to Meteor G for Mega Man to jump from WAZA's Dynamic Station through the rocket into the Meteor Server.
 * Numerous pieces of evidence in the Phoenix Wright: Ace Attorney games show up in multiple contexts in the same case, or even pop up in multiple cases as Continuity Nods. One example is from game 1, case 4,
 * In the first case of Phoenix Wright: Trials and Tribulations, a major piece of evidence is When she shows up in the third case, the
 * Not to mention the fact that
 * Anyone count how many times is used to object to testimony in the second case of Apollo Justice? Many lost count well before the judge commented on Apollo's repeated presentation of that piece of evidence.
 * At least 3 times;
 * The Case 4 knife in Ace Attorney Investigations: Miles Edgeworth. At first, it seems to be only significant because of its status as a murder weapon, but before the end of the case it's revealed to be . Shortly after, it's stolen by, who escapes. End of the story, right? Wrong. It shows up again in Case 5 (seven years later), . The full significance of the item is eventually revealed: But we're * still* not done; later on,
 * In Neoquest II, an RPG in Neopets, the sword you start off with is also the best sword to use against the final boss.
 * Paula's Pray ability in EarthBound starts as a useful, if unpredictable skill, that takes a back seat to her more reliable psychic powers.
 * Chrono Cross. Oh, Chrono Cross. There are party characters that serve this purpose.
 * Before that, Melchior in Chrono Trigger is an example of this with a Chekhov's Gunman: He first appears to just be some random merchant, then it turns out he's the forger of the Masamune, and then he turns out to also be.
 * That's right folks, we have a rare DOUBLE BOOMERANG in Melchoir.
 * While most spells in Loom are used only once, a few get used more than once - especially the opening spell.
 * Sometimes, you use a spell, and later you'll have to cast the same spell backwards to obtain the opposite effect (e.g. open/close)
 * In Mega Man 2, the Bubble Lead is pretty much useless against every other enemy in the game... until you get to Wily's, in which it's the only weapon that causes actual damage to it instead of healing it to full like every other weapon.
 * In Mega Man 3, the Top Spin is used once against a boss like all the other weapons, and then, it being the worst attack in the history of Mega Man, you probably never use it again...which is a shame, because the final boss goes down with one hit of it.
 * The Rolling Shield from Mega Man X is a bit unwieldy in regular gameplay, but it's the only special weapon that can damage Sigma's second form. Otherwise, you're stuck with charged X-Buster shots.
 * Full Throttle does this. It's a game about a Genius Bruiser biker. The extremely useful item in question? A tire iron.
 * It might even go so far as to be Chekov's Yo-Yo. You use it, then again, then again, then again, then again...
 * The Dig has a shovel serve as the puzzle solution 10 separate times. At one point the main character even comments, "What if I hadn't brought this shovel along? No, that's not worth thinking about."
 * In Halo, the Master Chief has to get the Index to activate the ring and destroy the Flood. In the very last moment Cortana takes the Index away and prevents the destruction of half the galaxy. In the end of Halo 3
 * The Sword of Gith in Neverwinter Nights 2 is the only weapon that can kill the King of Shadows, the Big Bad of the first campaign. In the second campaign, it is also the key to the Betrayer's Gate.
 * ...Completely ignoring the fact that Gith had nothing at all to do with the Betrayer's Gate, of course.
 * Which means nothing as the sword has had many owners since Gith, one of them simply used it for the key in the gate they made.
 * In Grim Fandango it's very easy at times to forget you have a scythe.
 * Grim Fandango has so many guns lined up on its narrative mantelpiece that it probably crosses the line into Chekhov's Armoury. At least one is actually a boomerang: Near the start of the game, the player learns of the two strange properties of the DOD's packing foam, and not too much later, uses one of them (that it expands like crazy when the two types are mixed.) Hours and hours later, nearing the end of the game, the player needs to remember the other property:
 * In Hitman: Blood Money, at one point you have to use a death serum to rescue a fellow agent by faking his death. In the final mission.
 * Done twice in Portal. First, at the end of the Companion Cube level, you have to Then, near the end of the game, one puzzle requires you to
 * An example of good game design theory.
 * In fact, the commentaries for many of the Half-Life games mention this style of game design. Show the player something, let them do that something, and then let them do that something while in a dangerous situation. Generally there isn't as much lag between the intial teaching and the usage of that skill, but it sorta counts.
 * The sequel has another example: near the beginning, you trick the system responsible for throwing out defective turrets into throwing out working ones and keeping the defective ones. Soon afterwards, GLaDOS throws turrets at you - which are defective.
 * Portal 2 is a game where nostalgia fights to create an unrelenting march of ChekhovsBoomerangs, all while introducing new ones.
 * Goldbob in the second Paper Mario game qualifies. After first appearing as a spectator in the Glitz Pit of no apparent importance, he and his family are fellow passengers on a train to Poshley Heights, where an incident surrounding the family serves as a Broken Bridge sequence. Later in the game, Mario is told that Goldbob has some sort of importance in a Bob-omb colony in the frigid wastelands and needs Goldbob's permission to use a special cannon.
 * In 7 Days a Skeptic you use the more than once.
 * And in the previous game, you were forced to use the "Salty bear on a stick" trick more than once. No, seriously.
 * In Fate/stay night, this occurs with Caster's Noble Phantasm Rule Breaker. First used in the Fate scenario to control Saber (thus leading to a Dead End). Then in Unlimited Blade Works and then again in Heaven's Feel
 * This goes all the way back to 8-bit videogames: in the Gargoyle Games' graphic adventure Marsport, one puzzle involves baking a cake. A later puzzle apparently involves baking another cake—but this turns out to be no longer possible. It transpires that the real solution to the second puzzle is to just use the same cake as before.
 * The in the third episode of Wallace & Gromit's Grand Adventures is used for 3 separate puzzles.
 * In Uncharted 2: Among Thieves, Nathan Drake finds an oil lamp made of a combustible resin, used to uncover a hidden map. This resin becomes important later on when it is realized to be the and is subsequently used to defeat the Final Boss through its combustible properties.
 * God of War has
 * In Wild ARMs Cecelia's Tear Drop item comes back several times.
 * Dragon Quest VII has a couple examples.
 * Early on in your quest, you meet the Fortune Teller Pamela, and help her out when her Cassandra Truth falls on deaf ears. After several adventures, you abruptly learn she has the knowledge required to fix another problem you've run into:.
 * The best example, however, is . This sits in your inventory after its first use and is easily forgotten, until you need to use it to  . Notably, you can do this long before finding out it's required.
 * In Suikoden V, you first use the sluice gates at the ruins near your castle to break out a flood to destroy the Godwin dam and bring back water to Lordlake. After awhile you seemingly forget it because of a series of events, including abandoning your castle from your enemies, until Lucretia tells you to go back to the ruins and open up the sluice gates again to flood the caste.
 * Broken Sword: Shadow of the Templars has the manhole-opening tool.
 * In Avernum 2 and 3, you get an ability called "Ritual of Sanctification" for a specific quest in each game. (It's used to purify an evil altar.) You can use it several more times throughout each game, and at least once it's needed to complete another quest.
 * In Metal Gear Solid 3, Big Boss begins the second and main storyline with two pieces of nifty but largely useless equipment, a suicide pill and an antidote which can be strategically used to play dead. As the player gets better camouflage packs and weapons it becomes less and less useful to the point where the player has no real need to use either until a certain boss fight later

Webcomics

 * In Flying Man and Friends, the main characters move into a house they "found" early on in the series. Five months later, the comic finally addresses who the house originally belonged to (a platypus named Platy).
 * While Pete Abrams of Sluggy Freelance seems positively Crazy Prepared with all those Chekhov's Guns he has hidden all over the place, we can safely say he certainly didn't plan the part about the man who sold Bun-bun to Torg in the first place and who was shown in one panel talking on the phone and saying there would be no refunds. Nine years later it's revealed Even the squiggle on his shirt gained significance.
 * In The Order of the Stick, Belkar aquires a Ring of Jumping. This first allows him to then later he lends it to Roy, who uses it to
 * Vaarsuvius learns the consequences of using a certain spell.
 * Sinfest: Glitter points really come in handy a lot.
 * When they're not Brick Jokes, Homestuck is full of elements that are used and then unexpectedly get reused later. This even applies to characters.

Web Original

 * The Whateley Universe authors love Chekhov's Gun and foreshadowing enough that this is getting pretty common. The way a blackmailer got a note past magical wards and into Poe Dorm comes back later as the way someone gets a tracker in Fey's luggage so she can get ambushed at Christmas. The Hawthorne girl in a Carmilla story who has toxic blood? She turns out to be Phase's cousin, who shouldn't even have mutant powers. Or the way that Counterpoint's power mimic ability works. Or Phase's little trick stealing Generator's underwear while she is wearing it keeps coming back. There's a ton of them.
 * In the very first Global Guardians story, Dogfight's status as a husband and father is remarked on by his teammates, as it is relatively rare for costumed crimefighters to be married, much less to be married with children. Years later, when Dogfight is killed rescuing people from the World Trade Center during the September 11th attacks, his family is brought front and center to add a bit more poignancy to the memorial for the attack's victims. They then disappeared into the background, presumably never to be seen again. In one of the last Guardians stories, Dogfight's oldest son reappears as a supervillain (having inherited his father's powers) seeking revenge on the Guardians, whom he blames for his father's death.

Western Animation

 * An episode of The Simpsons has Marge buying an impossibly absorbent paper towel brand and becoming enamored with its mascot. This seems to be just a setup for Homer and Bart to pull a prank on her, and apologize by going to a magic show that uncovers repressed memories of Homer finding a corpse in a quarry when he was a kid, but she then used the towels to drain the quarry of water so they can find the body.
 * The Simpsons actually uses this trope a lot, as a consequence of Halfway Plot Switch structure.
 * A lot of the stories in Donald Duck & Co. works with a Chekhov's Boomerang returning in the end and solving the plot.
 * This is a common usage in Danny Phantom. Nearly every Fenton invention will be used at least twice in the show, especially if it's unexpected.
 * Torgo's Executive Powder from Futurama. It's got a million and one uses.
 * And again more recently with Professor Farnsworth's "Disintegration" (actually teleportation) Ray.
 * In an episode of Batman Beyond, one of Mr. Freeze's ice ray guns comes in handy against a villain who can turn into liquid.
 * Old man Wayne actually pulls useful equipment from his gallery several times, such as his old utility belt when the current Batsuit gets corrupted, or the Grey Ghost's hat and goggles when he needs to hide his identity. It's awesome.
 * Occurs several times in TMNT 2k3, most notably in the episode "Same as it Never Was" in which the Turtle Tunneler, which had been introduced in the previous season as part of a different subplot, is used to kill an alternate version of the Shredder.
 * Zuko's broadswords in Avatar: The Last Airbender. Most viewers are under the impression that the gun was on the mantelpiece (literally), it was used once, and that was that. But he ended up using it almost as much as firebending and it changed the course of the series many times.
 * Katara's necklace also qualifies. After Zuko ends up with it, and he unsuccessfully tries to use it to force Katara into helping him, you think its purpose is over. Then they reach the Northern Water Tribe, and its real point in the story arc shows itself.
 * Aang's bison whistle.
 * And then there's Sokka's actual boomerang. It makes repeated appearances throughout the show, usually for comedic purposes... then it makes one final emotionally-charged appearance in the show's finale, just when you were least expecting it.
 * In an episode of Dexter's Lab where Dexter has to combat an alien life form that's possessed all his family members, he use's one of his self-manned robot inventions that he used previously to combat a group of bullies harassing him with dodge-balls even stating "i haven't used this baby since that whole dodge-ball incident".
 * In the South Park episode "Crippled Summer", after repeated failures to sabotage Jimmy's team, Nathan (the leader of the rival team) attempts to rig Jimmy's ukulele to explode, but it ends up used as an Xylophone Gag (since Nathan's plotline is a Deconstructive Parody of Looney Tunes). After the ukulele blows up in Nathan's face, everything involved in Nathan's previous plans come back to attack him again—a black mamba snake bites him, Tardicaca Indians shoot him with arrows, and a Tardicaca shark rapes him.