In the first Batman (1989), District Attorney Harvey Dent was played by Billy Dee Williams. Williams accepted the role with the knowledge and expectation that Dent would eventually become Two-Face. He reportedly had a clause put into his contract reserving the role for him in any sequels, which Warner Bros. had to buy out so they could cast Tommy Lee Jones. Williams would eventually voice the character in The Lego Batman Movie (2017).
According to Jim Carrey, he did not get along with Tommy Lee Jones, who told him that he hated him and his films.
Val Kilmer and Jim Carrey became good friends during filming. They bonded over the deaths of their fathers.
According to The Patriot News, while Tim Burton was still slated to direct the film, Micky Dolenz was considered to play the Riddler. (Dolenz would later play Two-Face's henchmen, Min and Max in Batman: The Animated Series (1992)). After Burton dropped out, Robin Williams was offered the role by Warner Bros., but refused due to being bitter about being used as "bait" to lure Jack Nicholson to commit to play the Joker in Batman (1989).
Jim Carrey's original idea to shave a question mark into his scalp had to be scrapped since he was due in court to finalize his divorce.
Bob Kane: (at around 1h 16 mins) Batman's creator appears in the film as a guest at Nygma's product unveiling ceremony. Kane can be seen reacting to Batman's entrance.
En Vogue: (at around 1h 6 mins) The R&B group appear as street walkers who appear after Dick steals the Batmobile and takes it for a joyride.