- Billing Displacement: 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 Teenage Mutant Ninja Turtles gets the cover.
- Channel Hop: Started first in Albedo: Erma Felna EDF, when it was an Anthology Comic 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.
- What Could Have Been: Initial work had begun on a Space Usagi cartoon, but was stopped after the failure of the superficially similar Bucky O'Hare. Similarly, Space Usagi was slated to make an appearance in the second season of Teenage Mutant Ninja Turtles: 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. 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.
Trivia / Usagi Yojimbo