George Clooney was originally attached to the project but when he left to do Batman & Robin, ex-Batman Michael Keaton was re-cast into the lead role. This caused no end of trouble for the Jim Henson's Creature Shop because they had designed their snowman animatronic specifically to Clooney's facial features and acting style.
In Charlie's bedroom, next to his bed, is a bust that has the body of Superman breaking out of chains, but the head of Batman. Michael Keaton is well known for his portrayal of Batman in 1989 and 1992.