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* BillingDisplacement: In the tenth issue of the original Fantagraphics run, the main story featuring the debut of recurring villain Jei is not on the cover, instead a side story featuring Leonardo of the Franchise/TeenageMutantNinjaTurtles gets the cover.
* ChannelHop: Started first in ''ComicBook/AlbedoErmaFelnaEDF'', when it was an AnthologyComic at first, for two issues, to then jumping to Fantagraphics comics and stayed there for 40 issues, including color specials, jumped to Mirage for less than 20 full-color issues, then stayed with Dark Horse for nearly 200 issues before moving to IDW in 2019, and then after 35 issues at IDW the series is set to go ''back'' to Dark Horse in 2023.
* WhatCouldHaveBeen:
** Initial work had begun on a [[https://www.youtube.com/watch?v=hlLPYn2km-U Space Usagi cartoon]], but was stopped after the failure of the superficially similar ''[[ComicBook/BuckyOHareAndTheToadWars Bucky O'Hare]]''. Similarly, ''Space Usagi'' was slated to make an appearance in the second season of ''WesternAnimation/{{Teenage Mutant Ninja Turtles|2003}}: Fast Forward'', but the appearance was scrapped when the season was cancelled.
** Originally, Keiko, the little girl that Jei starts taking along with him, was going to be possessed by Jei after his current host died. Stan decided that this was way too dark and had him possess another character instead. [[spoiler:Though it has no real relevance in the story it occurs in, it seems to finally happen in ''Senso'' after Jei gets atomized by the invading aliens. Keiko is a full grown adult by this point however, and is only seen as Jei as a cameo in a crowd of people.]]
** Notes for ''Senso'' reveal it might have featured the [[TheBusCameBack long-awaited return]] of Zato-Ino the Blind Swordspig, alongside his daughter.
** As early as the late 1970s, Sakai had planned a 2500-page epic graphic novel (before the term was even coined) about how humans came to displace FunnyAnimals with the protagonists being Nilson Groundthumper and Hermy and then Usagi, who would show up about 1000 pages in when the action shifted to Japan. Lord Hikiji being a human is [[TheArtifact a relic]] of this. The existing Nilson and Hermy stories are much more light-hearted than the Usagi stories, but Sakai had planned CerebusSyndrome to set in eventually. The story would have ended with the talking animals making a last stand and being ''wiped out''.
** ''Space Usagi'' was only created because Stan Sakai wanted to draw dinosaurs. We nearly got "Cave Usagi" set in prehistoric times.
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