* During the Roleplay/DCNation Olympics Arc, it was completely unintentional for Hades to actually kill Arsenal. The intent by the plot-runner and Hades-mun was just to get him high, removing him from the fight. The fact the Roy player ran with it and made Hades simulate a heroin ''overdose'' completely changed the ending, prompting the SadisticChoice the Greek Gods would force on Donna later.
* In Part III of ''WebAnimation/BartTheGeneral'', a door bell can be heard ringing in the background when Bart talks about throwing a sponge at a mirror.
* ''FanFic/QueenOfAllOni'': Chapter 14 has a scene of most of the Shadow Hand playing poker, and another of Right comforting Jade after her [[CallingTheOldManOut confrontation]] with her father. Neither was originally planned, but were added spur of the moment.
** Per WordOfGod, [[spoiler: Tarakudo]]'s brief cameo at the end of Chapter 16 was a last minute addition.
* [[TabletopGame/HoylesRulesOfDragonPoker Hoyle's Rules of Dragon Poker]] allows players to add cards from other games in and play them.
--> 230. If a card from another game is successfully snuck in after the session has begun and one round played, the card is valid and must be used in the manner intended by the original game.
* While writing ''SonicTheHedgehog'' fanfic, ''Fanfic/PrisonIslandBreak,'' author Breech Loader's computer apparently suffered a malfunction and 15 pre-written chapters - including those pertaining to the vital 'riot' arc - were lost. Breech managed to re-write 15 chapters in three weeks. By her standards for chapter lengths, that's about 52,500 words. That's 2,500 words ''per day.'' An awful lot of things changed.
** Part of the reason for the convoluted TriangRelations is because of the huge arguments between the co-authors as to the end pairing. Now that they have parted, the debate seems to have eased off - for now.
* ''{{FanFic/Starbound}}'' has a storyline in which the main characters need to shop for some stuff for Kagami's goldfish. What this stems from, is that author [=McKnight's=] beta reader (who is not into ''Manga/LuckyStar'') commented on some instructions Kagami gives to Matsuri and Inori at the end of chapter 2, initially assuming she keeps the fish in a bowl or tank. During some discussion from there, [=McKnight=] showed her a canon scene of Kagami feeding it, and she commented on the lack of features in the pond and how unhealthy that is for a fish.
** Its spinoff one-shot ''Birthday of Destiny'' contains several minor examples. For example, the dessert of choice was something the author and his family had for dessert on Thanksgiving of 2013, the time during which he was writing the first half of that fic. A few months later, towards finishing the fic up, he had realized a plothole in which Tadao was with his family while awaiting the main characters at Rokuna's house despite having stayed back at Konata's with Soujiro and Yui to fight off the Starman Jr. when everyone else had fled. What better way to clear that up than with a cutaway line by Miki.
* The authors of the ''Fanfic/SkyholdAcademyYearbook'' series admit that the bulk of what appears in the stories is a result of this trope. Many plots and details came about simply as a result of "Hey, you know what would be fun for them to do..." Since the entire series hinges on WishFulfillment, the result is that the reader gets to watch ''VideoGame/DragonAgeInquisition'' characters doing everything from attending the InUniverse equivalent of a Renaissance faire to going to the dentist. (ItMakesSenseInContext.)
* ''FanFic/ThePiecesLieWhereTheyFell'':
** The Hatchery System being modeled after the Residential Schools of Canada (a school system created for the purpose of removing children from the influence of their own culture and assimilating them into the dominant Canadian culture) was not intended from the beginning, but after a while (around the time Page pointed out, and Wind Breaker finally admitted it, that the Hatchery system was designed to break the griffon in him), it became intentional.
** Some of Anon e Mouse Jr.'s earliest contributions to the fic, prior to his being made a full co-author, also qualify - he thought of something (such as Vix-Lei mentioning that the members of the Questioning Order gave her the creeps), made the suggestion, and Evilhumour liked it and had him put it in.
* ''Fanfic/TheNewAdventuresOfInvaderZim'' has several examples:
** Originally, the creator of [[LostSuperweapon Project Domination]] was just going to be a nameless rogue Meekrob. At the last moment, while writing the scene, the author was inspired to name him Ch'rell as a ShoutOut to ''WesternAnimation/TeenageMutantNinjaTurtles2003''.
** The fight between Norlock and Slab Rankle in Episode 12 concluding with [[spoiler: Rankle launching Norlock away on a rocket]] was apparently a decision made late in that chapter's development.
** The entirety of Episode 15 was based on a proposed outline from one of the author's friends, which he liked so much he decided to include it. Also, [[spoiler: Squidman]] being involved wasn't in the original outline, but was added later in the planning process.
* ''FanFic/TheMLPLoops'': When writing what would become Loop 157.11 ("''Dragonshy'' with a different type of dragon"), Anon e Mouse Jr. intended to have Discord say "There's a plain statue [in the garden of Canterlot Castle]". He accidentally typed "plane" instead, and was hit with inspiration, leading to his not only keeping the line as-is but adding a CutawayGag where the princesses are in their garden and staring in confusion at a statue of a Sopwith Camel.
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