Invader Zim fanfiction The New Adventures of Invader Zim has had several examples of this, per Word of God by Zim'sMostLoyalServant.
Season 1
- Episode 4's chase across the city was supposed to include a trip to the Mall and an appearance by Slab Rankle. But because the writing of the chapter had dragged on so long, the author decided to cut that bit out and just wrap up the chapter.
- Similarly, Episode 5 was going to have several more Death Traps in the SEN library, but the author couldn't make them fit, so cut them.
- Steve and Viera weren't originally going to be siblings. However, making them brother and sister made it easier to bring them both into the story at the same time.
- In Episode 7, the automated emergency teleport off of the Meekrob ship was a last minute addition by the author, after he realized that the Alien Geometries he'd given the ship meant that no one would be able to just run out in time to escape the Self-Destruct Mechanism.
- Episode 9 was originally going to be about a spell going wrong and trapping all the main characters in their worst nightmares and having to team up to escape. Instead, the author decided to go with a lighter Dream Walker angle. Also, even after the change, it was supposed to focus on Viera, but was switched to Dib when the author decided having two chapters in a row focused on her would be too much.
- In Episode 11, it was originally going to be Viera's Eye of Fire amulet that was sacrificed to destroy the Central Root. But at the last minute, the author decided that it worked too well as a weapon for her to throw it away, so destroyed Dib's BFG instead.
- Episode 12 was originally titled "Norlock vs the Knock Offs", until the author realized that he spent more time fighting Slab Rankle than the Twilight parody's cast. So it was changed to "Norlock vs the Mall".
- Episode 15 wasn't even part of the author's original plan for the story, but was suggested by a friend. The author liked the idea and included it, but altered it quite a bit in order to remove a lot of M-rated content. Also, Norlock's role in the chapter (his presence in the daylight being justified by a weak Hand Wave) was removed and replaced by Squidman.
- Episode 18 was originally going to be about Team Save Earth and Zim's group having misadventures at a generic ComicCon knock-off, until the author decided that having them do so at that point would kill the momentum of the Story Arc, so it was shifted to Gaz instead. And that resulted in the convention being shifted to be specifically about video games, which inspired the idea of bringing in Iggins.
- In Episode 19, the author apparently juggled around which group would retrieve the Meekrob crystal and how the other groups would get its information anyway. Most of the scenarios thought up had to be discarded because they involved Skoodge betraying Zim to Tak and Tenn, which wouldn't have worked due to the Character Development that had happened in the process of writing the story.
- Project Domination was originally going to be a reality warping device, but the author felt that was too much of a game breaker, so just made it a really powerful Wave-Motion Gun.
Season 2
- Instead of ending up in a coma at the end of his first appearance, Havok was supposed to become Zim's hired muscle. However, this was originally planned during the period where Skoodge's above-mentioned betrayal was meant to still happen and leave Zim understaffed compared to the other factions. Between that not happening, and the author being given permission by the creator of Nyx and Ying to use them in the series, Havok seemed less necessary in that role and was given a different outcome.
- Episode 8 was originally going to actually show Nyx and Gaz arriving on Arcadikon and enjoying the purpose of their trip. However, the chapter ran long, so the author decided to wrap things up after the sequence on Foodcourtia and simply say that things went smoothly once they got to Arcadikon.
- Episode 9's Fan Convention — already a reworking of the original idea from Season 1 Episode 18 — was originally going to be sci-fi themed, before being shifted to fantasy instead.
- In Episode 13, Zim's nightmare was originally going to be about being captured by the humans and about to be dissected, only being changed to ending up back on Foodcourtia after a suggestion by a friend of the author's.
