Bugs Bunny was originally spelled with an apostrophe ("Bugs' Bunny")

In 1938, Warner Brothers writer Ben Hardaway directed a short film featuring a very sneaky rabbit. The cartoon was called Porky’s Hare Hunt, but the bunny that starred in it didn’t have a name. So, the best creative minds in the business got together and dubbed the up-and-coming star “Happy Rabbit.”

Ben Hardaway, whose nickname was Bugs, also directed he next short starring Happy Rabbit. As the animators drew up early image for the film, one of them labeled a sketch of the rabbit “Bugs’ Bunny,” to make it clear that the drawing was part of Hardaway’s project. The label was mistaken for the name of the character, and soon enough, all the animators were calling Happy Rabbit “Bugs Bunny."

From a post at Neatorama about interesting moments in the history of editing, where you will also discover that Catch-22 was originally entitled Catch-18.