The antagonist, Oswald the Lucky Rabbit, almost wasn't included -- kinda hard to be epic without a bad guy, you know? "Disney didn't own the rights to Oswald," designer Warren Spector explained to Game Informer. The Epic Mickey project was apparently of such importance, though, that Disney CEO Bob Iger made a deal with NBC Universal and "traded Al Michaels, a human sportscaster, for the rights to a cartoon rabbit." For what evil purpose was Universal keeping Oswald locked away? We may never know.
At Game Informer's website, see the first look at Epic Mickey's environments, along with more of that wonderful concept art.