In the brief time that Tim Burton was still considering doing a third Batman film, Riddler was the only villain that he planned on using. The idea of using Two-Face did not come up until Joel Schumacher joined the project.

Before deciding not to don the cape and cowl for a third time, Michael Keaton met with Joel Schumacher and declined to join the project after deciding that he did not like the direction in which Schumacher was looking to take the franchise.

During the party scene when Edward Nygma is introducing his new Box, the fantasies of one can be seen on a television screen. Later when people are dancing, on one of the screens in the background, you can see Batman! Someone must be having a Batman fantasy.

Batman creator Bob Kane has said Val Kilmer was his favorite Batman actor.

Mark Hamill was considered for the role of the Riddler. Hamill voiced the Joker in the Batman cartoons.

When Dick Grayson is trying to come up with superhero names for himself to become Batman's partner, one of the names he comes up with is Nightwing. Dick Grayson later becomes Nightwing in the comics, after his days as (the first) Robin.

When he practiced twirling his cane, Jim Carrey managed to break most of the furniture in his trailer.

Robin Williams tried out for the part of the Riddler.

Robin says, "Holy Rusted Metal Batman..." This is an obvious inside joke for all fans of the Batman series. As you may already know, Robin in the cartoon always said a phrase that began with "Holy...." and ended with a phrase that was not usually used in normal conversaion.

Alec Baldwin was almost cast as Batman.

At the time Sam Raimi was a popular "cult" director. When Tim Burton stepped down as director, he offered his services to the studio. He never got the job because the studio felt he wasn't a big enough name.

In the original Batman (1989), Harvey Dent was played by Billy Dee Williams. Williams accepted the role with the knowledge and expectation that Dent would eventually become Two-Face. Williams had a clause in his contract reserving that role in any sequels for him. Warner Bros. had to buy out his contract so that they could cast Tommy Lee Jones.

Rene Russo was originally cast to play criminal psychologist Dr. Chase Meridian when Michael Keaton was still attached to the project as Batman. However, when Keaton dropped out of the project and was replaced by Val Kilmer, Russo was deemed too old to play his love interest and was replaced by Nicole Kidman.

The doctor who summons Dr. Chase Meridian to Arkham Asylum at the end is named Dr. Burton. A nod to Tim Burton, director of the first two Batman movies, perhaps?

Brad Dourif was considered for the role of the Riddler.

Leonardo DiCaprio screen tested for the role of Robin.