Happens in most episodes of The Adventures of Jimmy Neutron, Boy Genius. In his most dire moment, Jimmy will have a "brain blast" and remember some trivial detail or offhand comment from earlier in the episode, and use it to save the day.
In the Adventure Time episode It Came From The Nightosphere, Finn records Marceline's sad song about her belief that her father doesn't care about her. After releasing him into the land of Ooo, Finn wants to get him back into the Nightosphere, and Marceline tags along, but just for her bass back. After getting her bass back and expressing her anger towards her father, Marceline storms off, until Finn pulls out the recording, and Marceline and her father reunite.
In the Adventure Time episode "Red Starved", at the start of the episode, Marceline finds a spoon. At the end, Marceline sucks out Princess Bubblegum's blood after being starved for quite a while, and Bubblegum uses the spoon to cure herself.
In Episode 14 of The Amazing Chan and the Chan Clan, Mr. Chan plays a violin at a pitch high enough to break glass, a seemingly random scene. Later, he has Alan play a recording of a violin in order to break the plaster molding covering the missing Winged Venus statue, thus solving the caper.
The Amazing World of Gumball lampshades and double subverts this one in "The Robot", where Bobert tries to take over Gumball's life. When it looks like the end, Gumball wishes some element that had previously been an inconvenience would appear and save him. At this point, Darwin leaps in to help...and gets knocked through the fence. Then, when Bobert advances on Gumball, the lawn sprinkler (which had previously sprayed Gumball when he was forced to sleep outside) comes on and shorts Bobert out.
Played straight in "The Job". Richard mentions early on that he sometimes eats the pizzas he's supposed to deliver. At the end, Larry finds out about this, giving him the excuse he needs to fire Richard, thereby averting the destruction of the Universe.
American Dad! episode "Hurricane!" parodies the whole idea of Chekhov's Gun with Stan's college javelin. Every time it's mentioned, the character looks directly at the camera and enunciates the words "Old. College. Javelin." Near the end of the episode, when it comes in handy to kill a bear Stan let into the house, Stan turns to the screen and says "Did you remember?" before throwing it and accidentally hitting Francine, instead.
It's subverted in another episode involving an evil hot tub. The salesman gives Stan a bottle of liquid which he needs to spray on the tub if he has any trouble with it. It isn't mentioned again until right near the end when he's propelled out of a second floor window, bounces off the saleman's car and another bottle falls out and lands next to him. Stan then remembers the salesman's words, but dies a moment later.
Amphibia: Midway through Season 2, Anne, Marcy and Sasha had to take the Calamity Box to three different temples to power up its three gems and reactivate it. Of the three, Anne only gets her blue gem charged halfway at the second temple; this causes her to retain her connection with it, allowing her to tap into a Super Mode so she can fight King Andrias in the finale.
Archer: God, I said the cap slips off the poison pen for no reason, didn't I?! Cyril: I know, I know, but I just assumed that if anything bad happened it-it would've been- Archer: No, do not say the Chekhov gun Cyril! That, sir, is a facile argument! Woodhouse: Also woefully esoteric.
That said, the Chekov gun DID manage to have its due as a Brick Joke, albeit MUCH later on in what might be the longest build up of a Chekhov Gun in all animated history. Archer warns Cyril about the Chekhov gun in the first season's episode "Training Day" which premiered January 14, 2010. In the season five episode "Archer Vice: Palace Intrigue: Part II," which premiered April 7, 2014 (over four years later), Archer shoots Cyril (who's wearing a bulletproof vest) with the Chekhov to distract a room full of people before it can be revealed that he just had sex. Archer, feigning shock, half-heartedly exclaims, "Oh. My God. The gun went off… for, like, no reason. Surprise."
In "Lo Scandalo", Malory refuses to remove her overcoat; at the end, it's revealed that this is because she's naked underneath.
In "The Archer Sanction", Archer reveals to Lana and Ray that the assassin in their six person mountain climbing group that they are to kill has killed high profile law abiding figures including politicians and Judges. By the end, the three other group members that are killed, (A german named Hans Hessler, an Italian named Mario Savino, and a Japanese woman named Michiko Ishikawa) are revealed by the killer to be Interpol Agents.
Back to the Future, "Roman Holiday". Doc's hologram projector shows up early in the episode with Jules and Verne fooling around with it, making it appear that their father is somewhere he isn't. It comes in handy when Doc needs to keep from getting thrown to the lions later in the episode.
Barbie As The Princess And The Pop Star: Keira's Outfit Microphone and Tori's Hairchanging Hairbrush helped them to capture the bad guy. The diamonds Tori and Keira put in their necklaces serve as a way to revive the diamond gardenia after the bad guy steals it.
The Wayne Manor technology fair sequence in The Batman vs. Dracula introduces a machine that stores and releases sunlight.
Early in the episode Trial, Gotham's new district attorney takes a batarang off of a gang leader Batman has caught. Near the end of the episode, when the inmates of Arkham Asylum have the two of them hostage and have strapped Batman to a table, the D.A. pulls the batarang from her pocket and throws it at a hanging lamp, darkening the room and allowing Batman to escape.
In the episode "Heart of Ice", Batman gets a cold after his first encounter with Mr. Freeze. Unable to convince him to stay at home and get some rest, Alfred instead gives Batman a thermos filled with chicken soup, referring to it as "the only way to fight a cold." Batman ends up using the hot soup to beat Freeze, and echoes Alfred's words when asked what it was.
Beavis And Butthead: In the episode "Roof", Anderson warns the pair that he desperately needs his new hearing aid or he can't hear anything without it, which they promptly throw away minutes later. Too bad he can't hear the pair calling for help at the end of the episode, and leaves them trapped on the roof.
The Ben 10: Alien Force episode "Pet Project" begins with Ben watching a cheesy horror flick where the villain brainwashes a girl's boyfriend. Later in the episode, the Villain of the Week enacts a similar plan, to which Julie reveals that she too has seen that movie and knows how it ends (The Power of Love breaks the brainwashing).
Bob's Burgers: Linda's pre-natal yoga tape in "Synchronized Swimming" ends up inspiring the routine she does with the kids near the end of the episode
In BoJack Horseman, Mr. Peanutbutter buys a bunch of spaghetti strainers because his agent suggested he come up with a movie idea surrounding them (as all of his ideas in the past have been completely outlandish). He eventually forgets why he bought them. In the season finale, a bunch of spaghetti is spilled into the ocean, causing mass panic. Cue his spaghetti strainers!
In "The Grand Opening!", when Butterbean and friends are setting up the café, Butterbean first discovers the case that reads "For the Fairy Finish" and the magic beans it contains. Later when nobody comes to the café and Jasper finds the invitations were ripped up, Butterbean remembers the magic bean case and uses one, the Flutter Bean, to call everyone in Puddlebrook (in addition to starting a World-Healing Wave) and officially open the café for business.
Early on in "The Perfect Picnic!", Cricket notes that ants hate cinnamon. Later during the picnic when hordes of ants come out of nowhere (because there's something sticky nearby and ants love sticky things), Cricket realizes said fact and borrows a jar of cinnamon which she uses to chase the ants away and save the picnic.
In one episode of Buzz Lightyear of Star Command, the team is on an alien spaceship headed for an inhabited planet. On the bridge, they try to figure out how to stop, steer, or otherwise control the spaceship, but all they find are things that activate windshield wipers and a cup holder. Later, the alien is revived, and shows them that the cup holder is actually the ship's steering mechanism.
In Season 1 "Episode One", lampshaded by Birdie when Owen gets suspicious about the sausages missing from his breakfast. Cole was giving the sausages to Shampagne.
In Season 1 "Skater's Circle", Paige is tasked to report the City Counsel Contract Committee Meeting which she finds boring, but Birdie lampshades this meeting will have an important impact later on.
In Season 1 "Rival Busker", when a hotel staff brings Paige and Molly to their room, the staff explains what a dumbwaiter is to Molly when she thinks it's an elevator for short people. Later on, when Anya runs away from her wedding, Molly walks past the dumbwaiter and hears Anya calling out for help when she gets stuck inside and Molly frees her.
When the gang go to get new scans of Hoton in "Allmageddon", it's noted that his stats are incredibly low. This later ends up being a key part of Peyton's strategy to defeat Drew's Hoton, taking advantage of the creature's lowered stats to win by turning the location to Fear Valley, which damages creatures with low courage.
The Song of Stasis, a mugic that freezes things in place, potentially forever, first appears in the minor episode "The Curse of Kor-Bek", where a supply of it turns out to be the titular curse. It's later used in Tangath Toborn's Heroic Sacrifice to stop the M'arrillians from flooding Perim.
Clone High: When Joan hears the Voice Of God in "The Last D Is For Disorder," it turns out it's actually broadcasts from a Christian radio station she's been picking up with her retainer that Gandhi dented earlier in the episode.
The Codename: Kids Next Door finale has Nigel's teammates tracking him down to a spaceship, thanks to a tracking device that was originally meant to be planted on the Delightful Children.
In a previous episode, a cigar-shaped laser that can change a person's age is used on the main villain (who had owned it). At the very end, we see the Delightful Children from Down the Lane take it. A couple of episodes later, that same device is used to age Numbuh One (and several minor plot elements from previous stories also make a re-appearance). This was actually the very first significant cross-episode use of this trope in this series. Until the DCs showed up with the cigar again, the average viewer most likely would have shrugged the first episode's ending off as a generic The End... Or Is It? ending, not expecting any follow-up whatsoever.
One of the previous plot elements that makes a reappearance in the above episode also provides a subversion: An episode begins with the gang training using a Humongous Mecha. Later, Numbuh Three calls it in to fight a giant turnip... that promptly smashes it to bits while she's locking and loading. (In fact, every single appearance of the training mecha ends with it getting smashed or whatever... including the one time it actually did anything useful.)
In one episode, it is established at the end that Numbuh Four cannot swim. This fact later becomes essential in "Operation U.T.O.P.I.A", causing Numbuh One to realize that he is trapped in a virtual world, because the person he perceives as Numbuh Four can swim.
The Boyfriend Helmet.
Lizzie's soup in Operation: S.N.O.W.I.N.G.
Chester's Happy Headband, another example that appears in "Operation U.T.O.P.I.A".
The Happy Headband is later used by the Galactic Kids Next Door on Numbuh One as a test to see how he'd react to becoming the child-hating adult president of the United States within a simulation of a Bad Future.
In Operation I.T, after Father becomes leaders of the Kids Next Door, he mentions how both adults and kids hate broccoli. Said hate for the vegetable is why he loses in the end.
The KND C.O.D.E.-M.O.D.U.L.E. is first mentioned when Father tries to steal it from the Artic Training Base in "Operation T.R.A.I.N.I.N.G.", and it is finally acquired in "Operation S.L.U.M.B.E.R." by the Teen Ninjas. When Sector V gets it back, it turns out to be a part of Father's plan to use the C.O.D.E.-M.O.D.U.L.E. to turn all of the KND into animals. But thanks to Tommy (who removed his registration in the module to keep from being trained), Father gets turned into a panther when his booger is injected into the module).
However, that, in turn, made Father a member of the KND, which made him eligible to become the Supreme Leader in "Operation I.T.". Nice job, Tommy.
Courage the Cowardly Dog: At the beginning of "The Tower of Dr. Zalost", Muriel cooks a recipe called happy plums, which she claims can make anyone happy. It later becomes the cure for Dr. Zalost's sadness.
The Critic: In the episode "Miserable" (a parody of the book/film Misery), Jay’s #1 Fan shows Jay a cardboard cutout of himself holding a book he wrote. She tells him she hooked it up to her Clapper, and demonstrates by clapping to it, and the cutout waves the book up and down and says "Buy my book!" multiple times. At the episode's climax, Jeremy breaks down the door to save Jay (she drugged Jay's glass of wine and tied him to her bed with strips of movie film, keeping him there for days). She madly lunges at Jeremy with a knife in her hand, when Jay claps his hands and triggers the cutout, hitting her on the head and knocking her unconscious.
This is the plot basis for 95% of all Danny Phantom episodes, with their numerous Fenton devices and occasionally Tucker's personal items.
This crops up from time to time in The Fairly OddParents!, like Cosmo's thoughts being elevator music in "Mind Over Magic", or Poof's smile being uplifting in "Wishology: Part III".
Parodied in Family Guy with Mayor Adam West giving Quagmire a banana and cryptically telling him that "When the time comes, you'll know". The banana ultimately proves useless in the end (Probably because Quagmire was Genre Blind to do a gag involving a banana peel).
Knowing Mayor West, the intended use hinted at in the cryptic instruction was to use it to have a nourishing snack. We are talking about the guy who swallowed a magazine and Stratego back in the eighties just in case he was ever in a hostage situation that dragged on so long he got bored. Speaking of which, a Chekhov's Gun there, too-in the episode where Brian holds Mayor West hostage, Stewie finds in the candy jar at his grandparents' house, a set of keys to an old model of car that isn't in production any longer. Mayor West agrees to drop all the charges incurred in the hostage situation provided they can give him a set of keys to that exact model of car. Quoth Stewie: "You're welcome."
In the Fantastic Four: World's Greatest Heroes episode "Strings", Reed suddenly feels like building a device. At the end of the episode, it turns out to be an amplifier for the Puppet Master's powers.
In "Franklin's Allergy" from Franklin, after Franklin and Bear get covered in mud after playing in a mud patch, Bear tells Franklin not to worry, that he'll just have a bath with his new bubble bath. It seems like a throwaway line — just something that would be mentioned in passing in a Slice of Life show. It turns out later that an ingredient in the bubble bath is the cause of the allergy mentioned in the story's title that keeps making Franklin sneeze throughout.
There's a more recent example that actually is a gun, too. In the beginning of "Lrrreconcible Ndndifferences," Farnsworth looks at an ad he put in a comic book for a "disintegrater ray" which is actually a teleporter (teleporters are apparently cheap and worthless in the year 3010). Later, an "Omicronian" that Lrrr had a one-night stand with appears holding the same kind of gun, and Ndnd steals it and shoots her. Later, Ndnd passes the gun to Lrrr and he is forced to shoot either Leela or Ndnd. He chooses to shoot Leela, but Fry does a pseudo-Heroic Sacrifice by jumping in the way. He is apparently destroyed, but then Lrrr's ex-girlfriend comes back and says the gun she had was just a stupid teleporter, and Fry is found in the Planet Express building.
A subtle one in "How Hermes Requisitioned His Groove Back." At the beginning of the episode, Hermes makes an offhand comment about stamping a form five times. The villain's fatal mistake in the end of the episode? Only stamping a form four times.
In "The Six Million Dollar Man" after Hermes puts his brain into an enormous robot body, Zoidberg takes his old body parts (he would sew them back together to use as a ventriloquist dummy) and Hermes asks if he's been eating them, to which Zoidberg retorts that he can't eat them because Hermes' skin is too spicy from all the goat he eats. After Zoidberg puts Hermes' brain back in his old body, Roberto, who was killed in prison earlier in the episode and whose brain Farnsworth inadvertently chose to replace Hermes' after the latter wanted a robot brain transplant, takes Hermes' robot body and uses his vegetable peeler to peel off a piece of Hermes' skin and eat it. Hermes' goat-laden skin causes Roberto to overheat and melt.
Used extensively in Gargoyles during the Avalon World Tour Arc. In almost every episode, somebody would relate some legend or fairy tale, and the characters would inevitably end up encountering it.
Sorta lampshaded during the arc when Goliath is explaining their adventures to a Laser-Guided Amnesia addled Elisa. Elisa asks if they really met the Loch Ness Monster, King Arthur, and the Holy Grail. Goliath says they haven't encountered the Holy Grail... Yet. Nearly a decade later, the Holy Grail would become important in the comic book series. Word of God has said this was intended as a Chekhov's Gun.
Early in Season 1, Elisa would get a partner cop, Matt Bluestone, who is very much Agent Mulder. He explains some of his conspiracy theories, which Elisa dismisses as bogus. She would encounter every single one a season later.
In one episode of Filmation's Ghostbusters, Tracy chomps down on a piece of bubble gum before the team enters a haunted castle. It becomes useful later. Does that make this Chekhov's Gum?
Gravity Falls combines this with a Brick Joke. When told she can choose anything she wants from the Mystery Shack for free in the first episode, Mabel picks a grappling hook. She uses it to save herself and Dipper from falling to their deaths in the season one finale, twenty episodes later. Also counts as a minor form of Cerebus Retcon, as the creator admits that the device was originally meant solely as part of Mabel's Establishing Character Moment.
In addition to the long-term guns like the one above, at least one gets loaded and fired seemingly Once per Episode.
Sam and Guy's matching briefcases. They accidentally take one another's briefcases near the end of Episode 1. It actually saves Sam's skin as the BADGUYS were hot on his trail.
Sam's Wildlife Protection Agent badge. It's to signify his role as such is a complete lie.
Guy's failed flight pack. He uses its side-effect of exploding to defeat the Goat in the final episode.
The Stovepipe newspaper Sam reads during his origin story.
Michellee's jar of beans. She spills them on the ground so that the Girooster can distract Snerz and the BADGUYS while she, Guy, and E.B. run off to catch up to Sam.
Michellee and EB's "friendship bracelets." They attach one of them to Snerz's wrist, and throw the other to the top of the hot air balloon airport tower to incapacitate him.
The BADGUYS calling card. It's to signify that BADGUYS is actually an acronym for "Bureau of Animal Defense - Glurfsburg Upper Yipville Section.
The Giroosters' uncanny resemblance to Mr. Jenkins. Sam uses this to trick Snerz when it looks like he really was selling Mr. Jenkins to the latter.
Snerz's living wig. It's Snerz's dirty secret, and once exposed, it turns him into a bald laughingstock, and it's later revealed that the wig, named a Flertz, takes over Snerz's entire corporation.
He-Man and the Masters of the Universe (2002) would routinely have Man-At-Arms be building something half seen in one episode that would be used an episode or so later. Sometimes, it would even become standard equipment.
The Hollow: The ishibo serves as this with the ever changing map coming in at a close second.
I ♡ Arlo: In "The Uncondemning", Marcellus gains an obsession for planting tracking devices, and proceeds to stick one to a fan boat. Said obsession is what allows him to reunite the main characters during the Final Battle; after the Big Bad destroys their only way home, he uses the fan boat, plus the receiver of which he attached to Bertie, to find Arlo and the others and regroup.
Invader Zim: "Plague of Babies": Early in the episode, we're introduced to the "Power Amplifier", a device which (evidently) "amplifies" whatever is fed into it — hence, when its input leads are plugged into Gir's head, it begins "sending out deadly waves of stupidness" (which briefly incapacitates Zim, but his PAK is able to "reboot" him). Then at the end of the episode, Zim uses this device to defeat the "baby" aliens.
Another example where Jimmy uses "Do penguins love meatballs?" to mean "yes", confusing the person he's talking to. At the end, he defeats the Rodeo Clowns by covering them in meatballs, which causes them to be eaten by penguins.
When Johnny Bravo was stuck on an out-of-control experimental bullet train that he took thinking it was the train to his Aunt Myra's house, he used the comically rock-hard pound cake that his mother made for her as an anchor to stop it.
"Mystery of the Lizard Men". The hydrofoil is used to escape the title opponents and the mirror Dr. Quest brings along saves the ship from a laser beam.
"The Robot Spy". The Parapower Ray Gun Dr. Quest is working on is used to destroy the title device.
"Arctic Splashdown". The snow skimmer the Quest team brings along is used by Hadji in an escape attempt.
"Calcutta Adventure". Dr. Quest's ultrasonic amplifier is used to destroy the bad guys by causing an avalanche.
"Pirates from Below". Jonny and Hadji's communication devices are used by them to communicate after Jonny is kidnapped. Dr. Quest uses the underwater probe's waldo arms to defend it against attack by the bad guys.
"The House of Seven Gargoyles". Strontium Glacier is noted as being dangerous, and a Hoist by His Own Petard causes it to destroy the villains. Professor Ericson's helicopter is used by Dr. Quest and Race Bannon to pursue the bad guys.
In the Justice League episode "Injustice for All", Green Lantern uses his ring to snatch a chunk of kryptonite away from Lex Luthor. Batman grabs it from midair and tucks it into his utility belt. Twenty episodes later, the kryptonite comes back into play when Batman takes it out of his utility belt to use as a weapon against Amazo, and once more against an alien-possessed Superman in Batman Beyond.
In Episode 11, the cast read a book series parodying Harry Potter, and Quack Quack goes into Troubled Fetal Position any time the main character's parents' death is mentioned. Later in the episode, Kaeloo transforms and needs to beat up Mr. Cat, but he makes himself look just like Quack Quack so she won't know who to beat up. She mentions the parents' death and the real Quack Quack assumes Troubled Fetal Position again.
In the Halloween Episode, Mr. Cat comes up with a terrifying and disgusting scary story, but circumstances keep preventing him from telling it. By the end of the episode, there's a bunch of zombies who have risen from the grave, Kaeloo and Quack Quack have been turned into zombies, and Stumpy is being absolutely no help whatsoever. To solve the problem, Mr. Cat tells them his story as they surround him. The storynote The story is told only to the characters and not to the audience is apparently so disgusting that everyone throws up. Kaeloo and Quack Quack revert back to normal and the other zombies die.
In Kim Possible, this was the finger trap from "The Ron Factor".
Almost every seemingly meaningless event in the first fifteen minutes of the Kim Possible movie became important to Dr. Drakken's evil scheme, from teen girl oriented magazines to bendy straws.
A literal example happens in King of the Hill when Buck shows off his fancy shotgun to Hank, only for it to be the central piece of the next episode's murder mystery.
Les Sisters: "Sisters Soldes" exaggerates the Retail Riot trope; at the beginning of the episode, when a clothing store that is having a sale opens its doors, everyone runs inside and tramples the security guard, an act which is witnessed by Marie and Wendy. Later in the episode, Wendy and Rachel are fighting over a dress, and when Rachel is about to buy the dress, Marie goes to the intercom and makes a fake announcement about clothes being sold for extremely cheap prices to anyone who buys them within the next five minutes. Wendy, aware of what will happen now, jumps out of the way while Rachel is trampled by a crowd of people at the checkout counter. During the confusion, Wendy grabs the dress from Rachel and pays for it, making her its rightful owner.
In a Road Runner/Wile E. Coyote cartoon, Wile E. sets up a metal gate in the middle of the road that pops up from the ground with the flick of a switch. Road Runner comes by, Wile E flicks the switch...and the trap fails to go off, even when he tries to set it off manually — not even to catch Wile E himself. Frustrated, he tries other attempts to catch the Road Runner. When he finally starts to catch up, they come across the metal gate, which finally pops up, and Wile E slams right into it.
There's another Road Runner cartoon where Wile E sets up a crate filled with explosives that will activate when someone picks up the glass of water sitting on top of it, setting up a sign reading "Last Water For 300 Miles". Road Runner then pops up behind him with a sign reading "Road Runners can't read and don't drink," flicks his tongue and zooms off. At the end of the episode, Wile E is dragging himself along, having escaped another explosion, exhausted, tired, and defeated. He notices a crate with a glass of water and, relieved, picks it up. He realizes what he's done just before the crate explodes.
A third one involves a huge squadron of glider dynamite bombs which he releases early in the cartoon. The rest of the episode involves the glide bombs showing up at inopportune times and foiling his schemes, usually in an explosive manner (natch).
The Looney Tunes Show: Near the beginning of "Shell Game", Bugs drops a faulty recliner off at the thrift store. Near the end of the episode, when Bugs confronts Cecil about his Staged Pedestrian Accident scheme and ends up held at gunpoint, Bugs recognizes the same recliner in Cecil's apartment. He tricks Cecil into using it, causing the turtle to get knocked out and disarmed.
Marvel's Spider-Man: at the climax of "Sandman", the Venom symbiote takes control of Peter just in time to save him from being suffocated by Keemia Marko.
The Dethphone, in its first appearance in Metalocalypse, a phone that the band created while they were drunk. It has spikes all over it, doesn't get nighttime minutes until 11 PM, and it's designed to eat up minutes. Murderface, after getting annoyed with it one last time, ends up using it to kill the troll they summoned early in the episode.
The entire premise of Mike the Knight is based on this. Mike's sword has been magically altered to be the gun. Each episode it is revealed, confusing Mike until he realizes later how to apply it to the situation.
Trini's lucky rock in "Dream Tube". After Molly and Tooey dismiss the rock as not being an agate, Trini uses it as her lucky rock. It later comes in handy when it's discovered to really be an agate and Auntie Midge buys it for $30, meaning that the kids have enough money to buy a tube.
Mr. Patak's canoe in "Have Canoe, Will Paddle". He builds one despite not knowing much about canoes. Later, it comes in handy when the kids use it for the canoe race after they get a hole in their original canoe.
In My Adventures with Superman, Jimmy's YouTube channel, Flamebird, initially seems to be a geeky hobby of his with little relevance to the plot. But after it suddenly blows up in popularity thanks to Jimmy consistently covering Clark's escapades as Superman, the sheer number of people following it makes it a valuable source of information, as Jimmy can contact a million people about what they're currently seeing all at once. In "Zero Day, Part Two", Lois and Jimmy use it to broadcast Superman's fight against Ivo to all of Metropolis and convince its people to shut the power to every building in the city to starve the Parasite armor of energy.
"The Glass Princess" has buswhoolie shedding season. It's mentioned offhandedly early in as a way for Molly and Shady to track the others, and late in the episode proves crucial to solving the conflict by providing a way for the heroes to make a convincing fake cloak.
Early in "The Golden Horseshoes, Part 1", Megan and the others are cared by a sound of howling wolves that's revealed to come from a music box that the Moochick owns. He then gives it to Megan, telling her that it might be useful in her search for the titular horseshoes. Later on, it proves extremely useful in frightening the Skree, allowing Megan to throw off their attention for long enough to steal the horseshoe they guard.
The show has one an entire season in the making. Discord has Mind Raped the mane six and Twilight has given up. She comes home to find Princess Celestia has been sending her scrolls all day. It turns out they're the letters that Twilight had been sending Celestia the entire previous season. They remind her what her friends mean to her and help her realize how to stop Discord.
The second season finale has Pinkie's "I never leave home without my party cannon!" statement return when she pulls it out of nowhere to wield against mooks. This took 17 episodes to return. Also a technique utilized half a season prior (in the ancient past in universe) to defeat the Windigos is used to defeat the Big Bad, only using The Power of Love in place of The Power of Friendship.
In the very end of "The Crystal Empire, Part 2", Luna pulls out a black book. There's no focus on it so you probably wouldn't pay attention to it until you rewatch the episode after seeing the season 3 finale, where the book is sent to Twilight and she is asked to complete a spell in it.
At the end of the Season 4 premiere "Princess Twilight Sparkle", the Tree of Harmony sprouts a mysterious crystal chest with six keyholes on it. Throughout the season, the mane characters encounter a Secret Test of Character according to their Element, which in turn bestows them a gift that emits a rainbow shimmer. The season finale "Twilight's Kingdom" reveals these are the keys in disguise, which turn into their true forms upon coming into contact with the chest.
In "Twilight's Kingdom, Part 2", the medallion Tirek gives to Discord as a sign of "trust" turns out to be Twilight's key, which Discord gives her after she shows she still considers him a friend after his betrayal.
During the episode “The Four Seasons”, we see Rebecca polishing Oscar’s lid. Later in the episode, Oscar uses his polished lid to reflect the beam of winter from the weather machine back at Thadius.
During the episode “Star Crossed”, Rebecca mentions having an invite to the play the orchestra and her are putting on, and tries to find it in her jacket. Later, the villains end up using that invite to find out the location of the concert.
In the first episode of Over the Garden Wall, "The Old Grist Mill", we are introduced to the main characters Wirt and Greg walking through an eerie wood, Greg leaving a trail of candy along the way. Later when it seems like the duo will be eaten by an Eldritch Abomination monster, Greg realizes that a piece of candy got stuck to Wirt's cape while he was making the trail, and that is what the monster is after. Once Greg tosses the candy away, the monster leaves them alone.
The tableaus shown in the intro. The girl and her dog are Beatrice before she was cursed to be a bluebird and the dog eating Greg's candy in episode one, the cat in the turkey-drawn carriage is Enoch's true form, the juggling gorilla at the circus is Miss Langtree's lost love Jimmy Brown, the figurines are the patrons and the tavernkeeper of The Dark Lantern pub, the old man is Quincy Endicott staring at the portrait of the "ghost" Margeurite Grey, the lady cutting the thread is Adelaide with the scissors that will break the curse on Beatrice and her family, the boat the boys are playing with is a replica of the frog ferry, the girl amongst the bones is Lorna organizing the remains of her victims, the fishing fish helps Beatrice rescue Wirt when he falls through ice, the rock is the Rock Facts rock Greg stole from Mrs. Daniels, and the girl near the well is the Woodsman's missing daughter, with the Woodsman right behind her.
The "work/dance" remote control in "I, Brobot" is used near the end to stop the Phinedroids and Ferbots from attacking Phineas and Ferb.
In "What Do It Do?" we have the father, Lawrence, giving a lecture to many students about the Earl of Whiskershire's eccentric life, which culminates in his creation of a scepter specially designed to spring traps. Later in the episode, Agent P notices the Earl's statue, which holds the scepter, and uses it to escape the many traps in Doofenshmirtz's out-of-control hover jet.
The map in Ferb's pocket near the start of "Summer Belongs To You!" comes in handy near the end, when Phineas and the gang are stranded on a desert island, and manage to get back to Danville by folding it into a giant paper airplane.
In Disney's film Recess: School's Out, TJ steals back his lucky baseball from the principal's office. At the end of the film, this baseball is used to foil the evil plan.
Rosie's Rules: The backpack in "Rosie the Dog Sitter." Rosie pet-sits Benito for the day and is given a backpack. Later, Rosie realizes that the backpack has things that Benito needs.
Rupert: In "Rupert and the Great Mephisto", Bill catches a hypnotized Rupert robbing his own home and snaps him out of it; the item Rupert was robbing was his Grandma Bear's old hand mirror. That mirror was later utilized by Rupert during the final battle with Mephisto, to turn his hypnotic powersagainst him and defeat him.
Scooby-Doo mysteries sometimes use this; the gang tends to find some odd clue which later becomes integral in solving the mystery they're in.
In The Simpsons Movie, Lisa tells Homer how to ride a motorcycle up and down a curved surface, which later enables him to save Springfield. Another is the sinkhole which Homer didn't fix, it later helps the Simpsons escape.
"The Blunder Years" has one of the most elaborate uses of this trope ever. Burly paper towels take up a good portion of the first act and then are not mentioned again until the end, when they are hastily re-introduced to resolve the main storyline. The Simpsons writers often note that events of the first act that set the main plot in motion usually have no bearing on anything else, so the possibility of this being a self-parody or roast are equally good.
This episode also had a throwaway line about Smithers' deceased father that later became important when the gorge was drained and Smithers the Elder's remained were unearthed. Call him a...Chekhov's Skull, if you will. *rimshot*
Another scene in the episode (which is a flashback 30 years ago) shows fire coming out of the newly-opened Springfield Nuclear Plant. Lenny and Carl laugh at the notion of working there, making it seem like Dramatic Irony, but later in the episode we see Mr. Burns and Smithers' father dealing with a reactor meltdown.
"The Dad Who Knew Too Little", in which one of the presents Lisa gets for her eighth birthday is a Chekhov's Laser Pointer.
Towards the end of "Who Shot Mr. Burns? Part One", there's a scene where Bart charges at Burns, only to stop when Burns reveals a holstered gun in his jacket. This turns out to be the one that shot him. A quite well-handled one, since we'd seen five or six people with guns already in the episode.
"Sideshow Bob's Last Gleaming" plays with this trope when an Air Force base whose annual air show Sideshow Bob is carrying out his latest scheme from includes a Harrier jet, with an Air Force representative pointing out how easy it is to pilot one. When Bob takes Bart hostage and tries to flee the Air Force base he attempts to steal the same Harrier jet...and then drives it right into a ditch. He gets away soon after by stealing the Wright Flyer, which was also showcased at the air show.
In "Boy-Scoutz 'n the Hood", Homer goes on a rafting trip with Bart, Ned, and Rodd, but immediately loses the map after trying to make it into a paper mache hat. When Ned asks Homer if he's got the map, he instead pulls out a map that shows every Krusty Burger in America. While it initially seems like a throwaway joke, eagle-eyed viewers might notice that it also shows one sitting on an unmanned oil rig - and at the end of the episode, when they're lost at sea, they find it using the map and are saved.
The "No Dogs Allowed" signs in Snoopy, Come Home, which had been tormenting the beagle throughout the film, until the end, when one sign on Lila's apartment building got Snoopy out of his moral obligation to her, allowing him to return to Charlie Brown.
In an early scene of the Russian The Snow Queen film, (the animated one) a bird freezes to death to save her babies from the cold, and it becomes more important later on in the film rather than just serving as a Tear Jerker.
Sofia the First: "Make Way for Miss Nettle" opens with the clock tower figurines moving around the clock when it chimes. It's later revealed that this is where Flora, Fauna, and Merriwether's spell book, which Miss Nettle wants to steal to become more powerful than them, is hidden.
In the Adventures of Sonic the Hedgehog episode, "Sonic Breakout", Tails gets a free poster of Sonic in the latest issue of the Crack Ups comic book, which leads to a minor complaint by the hedgehog himself since he's shorter on the poster. It comes up later when he sticks it on Grounder's back due to a security system specifically programmed to shoot at anything "hedgehog blue".
In a Season 1 episode of Sonic the Hedgehog (SatAM), the Freedom Fighters discover a species of "metal-eating" plants that instantly corrode metal into dust upon contact. The plants' harmless seeds are harvested before the episode is over; they aren't ever brought up again directly, but come the final episode of the series, we discover that Rotor's been developing metal-eating water balloon-like thrown projectiles, implied to be the result of studying the plants.
The Movie has Cartman's V-Chip in his brain. Cartman had it put in to prevent him from swearing. The chip then shorted out when it absorbed most of the electricity while Cartman rescued Terrence and Phillip from the electric chair. And now that he found out that swearing causes bolts of electricity to shoot from his hands, he's able to take out Saddam's undead army.
The "goo" that came out of the Rob Reiner at the end of "Butt Out" becomes a plot point in the episode "200".
"The Death of Eric Cartman" establishes that the boys love KFC. After the boys decide to start ignoring him after eating all the chicken breading, he becomes convinced that he is actually dead, confirming it to himself when hearing reports about what he ate clogging the toilet as referring to rupturing his colon.
The plot of a latter episode, "Medicinal Fried Chicken" revolves heavily around KFC.
The "Kenny born for the 52nd time" gag at the end of "Cartman Joins NAMBLA" becomes a major plot point in the "Coon and Friends" trilogy.
In "Margaritaville", Kyle holds a Sermon about the economy, saying he applied for an American Express Platinum card to prove a point, and holds it up to show his audience. Near the end of the episode, he uses that same credit card to pay off the town's debts.
The paperclip on a string in "Sandy, SpongeBob and the Worm" provides great usage much later.
The luxurious egg from "Whatever Happened to SpongeBob?" is what restores SpongeBob's memory in the climax.
The bathroom key from "Ditchin'" is what saves SpongeBob from his Disney Death in the tar pits.
Star Trek: The Animated Series: In "How Sharper than a Serpent's Tooth", when Dr. McCoy is teleported to Kukulkan's ship, he mentions that he has his medical kit with him. Near the end of the episode a Capellan Power Cat has gotten loose. Captain Kirk uses a hypo from the kit to inject the Power Cat with a powerful sedative, ending the threat.
"Crisis Point": Boimler mentions early on that he used the crew's private logs to develop extremely accurate simulations of them. This means that the simulation knows private facts about them, which in conjunction with Mariner's movie leads to Holo-Freeman reveling her relation to Mariner.
The scrapped shuttle Sequoia, which has been sitting in pieces in the lower decks workshop all season, is used by Shaxs and Rutherford to board the Pakled ship.
All of the contraband weapons that Mariner has been collecting are used by the crew to fend off the Pakleds when they beam aboard the Cerritos.
At the start of the episode, it's mentioned that the Titan is in the area. The ship warps in just in time to rescue the Cerritos from three more Pakled ships.
Star vs. the Forces of Evil: Subverted when Star and Marco infiltrate St. Olga's School for Wayward Princesses and Marco is locked in a chair to be rehabilitated by an instructional film. Being Genre Savvy about institutions after having watched every prison escape movie ever made, he attempts to pick his shackles with the bobby pin he was keeping in his mouth up until then, only to find that they can't be picked and he flicks the pin away. Double subverted when at the end of the episode Ms. Heinous uses it to track Star and Marco back to Earth.
The pilot episode of Steven Universe has, after Steven's abuse of a time travel MacGuffin attracts the attention of a powerful alien, Garnet pull a rather out-of-character move by declaring "Steven, why are you such a buttface?" When the Crystal Gems are beaten, Steven remembers the insult and uses the MacGuffin (which is triggered by him coming up with the perfect comeback to an insult) to go back before the attack and save everyone. Garnet's reaction to the comeback implies she did this deliberately.
In the series proper, one episode has Greg use duct tape to fix his van. He later uses it to fix a crack in the geode.
In "Gem Glow", the employees at The Big Donut let Steven take home a Cookie Cat-themed freezer when he is upset that the store is discontinuing sales of the ice cream sandwich. When a Corrupted Gem gives the Crystal Gems a run for their money later in the episode, Steven hurls the freezer at the Corrupted Gem, electrifying and defeating it.
In "Lion 3: Straight to Video", one of the items in Lion's mane is a bubbled bismuth that's visible for about a second. Two seasons later in the 100th episode, Steven accidentally breaks the bubble, causing her to reform.
The Season 1 episode "Marble Madness" has Steven list off some of the people he knows or is friends with around Beach City to a pre-Heel–Face Turn Peridot when trying to explain if humans were still around on Earth. Fast-forward to the end of the fourth season, and that list turns out to be why Aquamarine and Topaz were kidnapping his friends.
An episode involves Dark Ace getting his hands on a suit of huge robotic armor. At the same time, Finn gets enthralled by a transforming puzzle (like an uber Rubix). It kept being conspicuously brought up when the other characters were trying to figure out how to stop Dark Ace. In fact, both the puzzle and the armor were said to drive people insane. It was working up to some revelation that either it could be used to distract Dark Ace as he falls into dementia (it's even mentioned that he's got diminished mental ability due to the suit) or that somehow the puzzle and suit are related. Turned out to be mostly red herring though: An offhanded comment about powering it up when it went out of juice was key to victory. The toy itself was unceremoniously melted in the episode's denouement.
Played straight with the Oracle Stone from the Forbidden City in season one, which turns out to be a very, very important item in the final (and only real arc) of the series, with serious ramifications when it falls into the wrong hands.
This was parodied in an episode of Stripperella, when the tech group gives Stripperella a penny disintegrator and a really old guy gives her an over sized cellphone, and she is later trapped in a jar being filled with pennies. Unfortunately, the disintegrator takes a full minute for each penny, so she ends up using the cellphone to break the jar.
When Kryptonite was first introduced in Superman: The Animated Series, Lex Luthor trapped Lois and Superman in an exhibit in his new museum with the Kryptonite and attempted to kill them both with a robotic dinosaur. Luckily, they had learned Kryptonite's radiation could be shielded with lead, and Superman remembered earlier from listening to a tour guide that some cups in the exhibit were, in fact, lead.
The first Kryptonite episode had another example. When Lois is thinking, she plays basketball with her trash can and crumpled balls of paper. Later, this skill becomes vital to getting the kryptonite into the lead cups -they're guarded by an electrical field.
The same episode also sets up the origin of Bizarro later that season. Luthor explains that Superman, weakened with Krytonite, actually bled while fighting the robot dinosaur. This granted the villain a rare opportunity to collect his DNA for cloning.
A Thousand and One... Americas: Early on in the twentieth episode, Chris notices that a goldsmith (Undapawa) accidentally let a golden statue made by him fell off his bag. Chris grabs the object and quickly runs to the man to give it back to him. Later in the episode, an antagonistic businessman falsely accuses Undapawa of having performed a trade with him by using fake gold statues made of clay, and throws it onto the floor so it breaks and he can prove his point. Chris then grabs the pieces of the statue and realizes that it wasn't made by Undapawa, as the recalls that the one he grabbed early on was heavier due to it being made of actual gold. The evil man disregards the observation (as he knows his lie has just been exposed) and tries to abduct Chris and Lon. Cue a fight.
In Thunder Cats 2011 young Catfolk Prince Lion-O purchases a suspected piece of Lost Technology from Jorma, his Friend in the Black Market. After seeing an enemy Lizard Folk use an identical object to blow up a wall while invading his city, Lion-O realizes his find is a Sticky Bomb, In Working Order, no less. He grabs some others he's secreted away to join the fight against the Lizards, saving his father Claudus and brother Tygra by using the bombs to blow up some of the Lizards' Walking Tanks. Amongst Jorma's many other Cow Tools the sharp-eyed viewer can also spot at least one Ro-bear Berbil arm.
Total Drama Island: In episode 8, Beth picks up a souvenir from the challenge of the cursed island. It gives their team "bad luck" for three episodes, and leads to her elimination when her team discovers she has it. However, it is also partially averted in that Chris keeps reminding us of it in recaps, because Viewers Are Morons.
In one episode of Total Drama World Tour, the prize for winning a challenge is an electric meat grinder, which Heather promptly throws out the window despite being warned not to. Next episode, the teams have to stuff sausages, grinding meat by hand. Instead of using, say, an electric meat grinder.
Like with James Bond's Q, every gadget that Jerry gives the girls in Totally Spies! gets used in that episode, many of them with even more ridiculously specialized uses. He's still at it in The Amazing Spiez!.
Transformers Beast Wars had several set up in its first season, such as the alien artifacts that were lying around. Rhinox notes that one of the moons doesn't seem right, that it's much lighter than it should be, a Chekhov's Gun that gets fired twice. First it's actually an alien super-weapon that is designed to wipe out all life on the planet, because it is a giant experiment and the Vok needed a way to reset it if it got contaminated, such as from a bunch of marooned time-travellers. Second, it means the planet only had one natural moon, and the artifical moon being destroyed revealed that they were on Earth All Along. In the first episode, we briefly see a golden disk, a relic Megatron and crew stole, intending for it to lead them through time to a prehistoric Earth. After initially believeing they were NOT on Earth, the disk became irrelevent, until Season 2, when the revelation that they actually were on Earth meant that the disk held knowledge of the future, and large portions of that season's plot revolve around the disk and the knowledge it contains.
Blackarachnia's helmet, as revealed at the end of the Transformers: Animated episode "Predacons Rising." As seen in a flashback in "Along Came a Spider", while Blackarachnia, Sentinel, and Optimus Prime are exploring the Spider Planet just right before they accidentally leave Blackarachnia behind in the caves, causing her to mutate into her current form, her helmet can actually be seen lying next to a Decepticon ship near several energon cubes.
Done rather subtly in the Transformers: Prime episode "Alpha, Omega": Late in the episode, Smokescreen explains how he was able to use an artifact called the Phase Shifter to protect himself from Megatron's attack. The Shifter was in fact on his arm the entire time, just simply not mentioned or noted until it was brought up.
In the Season 1 episode "Stronger, Faster", Ratchet creates an incomplete Synthetic Energon that boosts his physical ability, though not enough to keep him from being injured by Megatron, and allowing Knock-Out to collect some of the Synthetic Energon. Two seasons later, it turns out that when Synthetic Energon is combined with Cybernucleic Acid (the Transformer equivalent to DNA), it produces Cybermatter that can be used to restore Cybertron.
Uncle Grandpa: In "Jorts", Mr. Gus gets Tiny Miracle the Robot Boy to take off his jean-shorts, but decides it's taking too long and to do it himself. At the end, he comes to accept the jean-shorts, right before Tiny Miracle completes the task.
Another example in "Bad Morning". The episode opens with Pizza Steve eating ice cream for breakfast, but falling asleep before he can finish it. At the end, Mr. Gus uses it to give Uncle Grandpa a sugar crash in order to get him to go back to sleep so he can wake up on the right side of the bed and stop having a bad morning.
In "Shower Party", Pizza Steve wants to throw a party in the RV but Mr. Gus reminds him what happened the last time they threw a party when Uncle Grandpa was inside (he committed a party foul). Later, when the party they throw gets out of hand, Mr. Gus realizes there's a way they can get everyone to leave.
Mr. Gus: Remember earlier when we flashed back to that flashback? (Mr. Gus and Pizza Steve remember themselves remembering Uncle Grandpa's party foul) Pizza Steve: Oh yeah, I knew that was gonna be significant to the story.
In "The Hat", Sylvia's obsession (and Wander's dislike) over jellyfish pie is what leads to the two being freed from the giant worm.
Wander's famous motto, "It never hurts to help!", becomes quite useful in "The Hole...Lotta Nuthin'", as Hater said it which accidentally causes Wander to snap out of his Heroic BSoD and make the best of it, which also leads to Hater detaching one of his arms to plug up the black hole.
Winx Club: In Episode 7 of the second season, a character gives a few pixies some jewels, and makes a point about how the season's Big Bad is trying to get into some place called Realix by collecting four pieces of something called the Codex... and that there is another way into this Realix place. After we gradually learn what all that means, in Episode 26, the season finale, it's revealed that the other way is via those jewels, which had not been seen since they were given to the pixies.
In the original, however, she just gives them the jewels and says, "As you probably know by now, the situation is extremely critical. These must remain secret. You know what to do." We gradually learn all of the above information as the season progresses (instead of in one fell swoop early on as above), and one of the later episodes also has a flashback to that scene (which the dub cut out).
Season 4 provides a subversion: One of their smaller missions ends with the ethereal fairies giving them a Chekhov's Gift that can be used to save exactly one person from death. There was quite some speculation over who it would save, and given this show's nature, it would be used usefully, right? Well, the next episode sees Nabu getting his life drained from him, and naturally Layla decides to use the power on him... and then the season's Big Bads take the power from her and waste it on a limp flower.
The 4Kids dub provides an example of Chekhov's Gun being undermined via editing: An episode has Musa and Layla talking about what to perform at a concert she's having, and Layla suggests (and shows) some sort of rain dance. That information later becomes useful to defeat Stormy with. But in the dub version, they just show Musa defeating Stormy with the rain dance, and then show the scene with Musa and Layla discussing the concert, where Layla's dancing is now just her showing her dance, with any rain-related significance removed. Clip.>
And the reverse has happened a few times before: While Bloom just randomly shields herself from a Trix attack, the dub has an off-screen Tecna telling her to use a "Griselda bubble", a shield that their teacher demonstrated in class at the start of the episode. Also, an S1 episode has dub-only dialog of Bloom reading up on a protection spell for an exam. Guess what she ends up doing in said exam.
If you're into Wild Mass Guessing, you could also argue that they turned a straight use into a subversion, by having Tecna's Sphere of Truth spell turn out not to have worked. To everyone else, it's a Dub-Induced Plot Hole.
In "Zadie's Shell Shuffle," JunJun sings a song about the colors of Mr. E's shell garden. When Zadie accidentally messes up the shell garden, she uses JunJun's song to figure out the pattern the shells should be in.
In "Zoom In Zadie," Zeke mentions that Super helped him learn to draw a square when he was having trouble learning. Later, Super and Malik attend the class and Super help Mr. E make a perfect square.
In Young Justice (2010), Robin finds an arrow in "Schooled" and Kid Flash saves it as a souvenir. Artemis would use this arrow in "Homefront" to save the rest of the team.
Dr Fate's helmet in "Denial" would become an important point in "Revelation" as Aqualad would wear it to stop the Injustice League It would also come in play in "Misplaced" where Zatana uses it to fight Klarion, and her father Zatara becomes Dr. Fate permanently to convince the helmet spirit's Nabu to let her go.
over who it would save, and given this show's nature, it would be used usefully, right? Well, the next episode sees Nabu getting his life drained from him, and naturally Layla decides to use the power on him... and then the season's Big Bads take the power from her and waste it on a limp flower.