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* ''[[http://lparchive.org/LetsPlay/Boatmurdered/ Boatmurdered]]'':
** This well-known [[LetsPlay succession game]] of ''VideoGame/DwarfFortress'' has an example -- an early ruler builds a catapult in the southern parts of the outdoor plains to take out problem elephants, get rid of surplus stone and train siege operators. Due to a lack of manpower and constant attacks, it never sees use and isn't even mentioned again. [[spoiler:When a later ruler allows magma flow from Project Fuck The World to reach the southern parts of the map, it sets the catapult on fire. The smoke clouds and spreading blaze from that one structure ultimately lead to the fortress's downfall.]]
** Then there's the later succession game ''[[http://lparchive.org/LetsPlay/Headshoots/ Headshoots]]'', and The Inexplicable Room and the path to it. Nobody remembered making either, no ruler could find how it connects to the rest of the fortress, and it could only be found via the 'find unit' function. Even a majority of the dwarves couldn't find their way in or out. [[spoiler:The final turn, where the two unbelievably-strong soldiers Holistic Detective and [=Nemo2342=] were [[VideogameCrueltyPotential skeletonized and sent against the entire fortress]], the only surviving dwarf hid in the path to The Inexplicable Room.]]
* ''[[Creator/{{Dropout}} CollegeHumor]]'''s game show spoof ''Game Changer'' managed to do this ''completely improvised'' in its MusicalEpisode, "The Original Cast Recording". In the song welcoming her to town, [[TheHero Alexa]] is told by a local how to use local slang, to avoid a particular woman (the villain), and not to eat too much of the local tuna. At the end of the musical, when the villain is making a HeelFaceTurn to become a train conductor, it's announced that there's a convenient opening because the local conductor just died...from eating too much tuna.
* ''Podcast/DeathByDying'' uses this in its first episode. The Cragmire canon fires whenever a person in town dies and the cannonballs land in the field outside of the Hudson farm. At the end of the episode [[spoiler:the murderous Bernard Hudson is killed when she is hit by a cannonball [[ItMakesSenseInContext fired to honor the deaths of her deceased husband's goats]].]]
* During the ''WebVideo/DoubleLifeSMP'', this trope takes place several times:
** On Day 4, Ren and [=BigB=] rig a trap using a zombie spawner, and use their generated zombie "army" to crash Bdubs and Impulse's pool party at the end of the episode, [[spoiler:killing them in the chaos that ensued]]. This returns as a ChekhovsBoomerang on Day 5, when [[spoiler:Scar digs into the zombie pit and loses his and Grian's first life trying to escape]].
** The modded mechanism where Sculk Sensors can be triggered by the sound of someone's voice. At first, it's just an obstacle for anyone venturing into the Ancient City to get enchantments in order to avoid spawning the Warden in, but on Day 5, Joel and Etho rig a TNT trap using one, [[spoiler:killing Scar (and thus Grian) while he was trying to invite everyone to a funeral for Jimmy and Tango (who had been KilledOffForReal earlier the same episode)]].
** At the start of Day 5, Grian attempts to prank Scar using a falling dripstone stalactite, which almost kills the both of them. At the end of the episode, [[spoiler:he skewers Ren with a falling stalactite and causes him and [=BigB=] to be KilledOffForReal with the same trick]].
** At the end of Day 5, Grian makes a grave in the mountains for [[spoiler:[=BigB=] after accidentally killing him by proxy]]. Scott stumbles across it on Day 6 and he later [[RobbingTheDead steals the sand from the grave-site]] to make TNT, which is later used to either distract the two Wardens the Red Lives ferried up to the surface... or to [[spoiler:die from suicide by self-detonation]] at the end of the series.
* In WebVideo/{{Dream}}'s first [[https://youtu.be/vXS1pXWslxs?t=993 Death Swap video]], Dream finds [[spoiler:an enchanted golden apple]] in a chest, which is the single item that [[spoiler:turns the tables on George when he puts his trap in the Nether]].
* In an early ''Literature/FineStructure'' story, Seph thinks to herself that Mitch, who can phase through things, could kill someone instantly by materializing his hand inside their head, but she doesn't think he'd do that and doesn't mention it. Near the end of the series, he does just that.
* At the start of ''Literature/GreekNinja'', Sasha mentions having odd dreams, which although it's implied there is some importance to them, they are otherwise dismissed, until it's revealed in the fourth chapter [[spoiler:that they are actually memories from Sasha's previous life as Eli of Thrace]].
* There's an interesting anecdote about ''Literature/JohnDiesAtTheEnd'' regarding ''Camel Holocaust'', the "song" that John wrote for his band early in the book. In the original webnovel, the protagonists have to stall a group of monsters at a later date by playing ''Sweet Child O' Mine'' on a set of guitars they stole from Elton John. When the book was to be put into print, however, the issue of copyright came up. The author stared dumbly into space, scratched his butt, and realized that he had left Chekhov's Gun sitting in his back pocket. Thus, the day was saved by [[strike:Fat Jackson's Flap Wagon]] [[AGoodNameForARockBand Three Arm Sally]].
* At the beginning of ''Blog/JustAnotherFool'', there's a random vignette about Logan's watch. Later, it becomes a major clue for a puzzle.
%% * A weird little news brief from [[http://www.theonion.com/articles/gun-goes-off-during-lifes-third-act,17286/ The Onion]].
* ''Website/SfDebris'' has one in his review of ''Anime/PuellaMagiMadokaMagicaTheMovieRebellion'' where he begins the review with reading parts of the tale of the Soldier and Death in which a soldier manage to trick Death into a magic bag. He returns to it later when [[spoiler:Homura forcibly split Madoka from Madokami]].
-->'''Chuck:''' (In the beginning of the review) Soon he laid there in his own sickbed, waiting for the arrival of the woman, who was the embodiment of Death, to come and take him away. And when he saw her there, near his head, coming to take away the soul of this old soldier, he asked her: ''Do you know what this is?''. She looked and said: ''It's a sack''. ''Well if it's a sack,'' he said ''Get into it!'' And immediately she was trapped within the sack of the soldier, who bound it tightly and felt quite, quite pleased with himself.
-->'''Chuck:''' (Later) The moment has finally arrived. After all the endless fighting [[spoiler:Madoka has come to claim this soul, and all this old soldier can say to her is: ''If it's a sack, Get into it!'']]
* At the beginning of Eliezer Yudkowsky's article [[http://yudkowsky.net/rational/the-simple-truth "The Simple Truth"]] the author uses an analogy to advise people not to abandon the concept of truth, using the example that even when gravity wasn't understood, people had the common sense not to walk off cliffs. By the end of the story,[[spoiler:Markos Sophisticus Maximus denies the concept of truth, and walks off a cliff.]]
* In the first chapter of ''Literature/TheTimTebowCFLChronicles'', it's revealed the Canadians [[ComicallyMissingThePoint fundamentally don't understand the purpose of locks]]. Much later, the Toronto Argonauts (with guidance from their few American members) realize they can evade a massive ZergRush from the Atlantic Schooners by luring those opposing players into chambers on a (non-Canadian) aircraft carrier, and just locking them into the room.
* ''Literature/WhateleyUniverse'':
** The Whateley Weapons Fair at [[SuperheroSchool Whateley Academy]]. Phase is asked to try a forcefield disruptor by an inventor who has very little cred. It's just the thing Phase needs at the end of the Fair, when someone's weapon makes everything else go haywire. Then, much later, Phase uses another one of the forcefield disruptors in a fight, and it blows up on her.
** The Weapons Fair is turning into a ChekhovsArmoury. The attack devise in Knick-Knack's 'lava lamps'? Used to attack Phase in a much later novel. Phase's run-in with Kew and the Spy Kidz? Important in "Ayla and the Networks". There seems to be a lot of these.
** Face it, the Phase novels are nothing but Chekhov's Guns. Some of the background issues in Ayla 1 turned out to be key plot points in Ayla 6. Phase's concern with the New Olympians in Ayla 4 turns out to be critical in Ayla 7. Delta Spike's rambling in Ayla 7 about a course she took last year turns out to give Phase a crucial clue early in Ayla 8. And those are just some of the ones where the gun doesn't get fired in the novel where it's shown.
* At one point in ''Literature/{{Worm}}'', Doctor Mother mentions that one of Cauldron's capes can DePower parahumans. [[spoiler:It gets used on Taylor at the end of story.]]

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