According to actor Pat Hingle (Commisioner Gordon) in his Special Edition DVD interview, there was a flashback scene shot, but not used, that reveals that after Bruce Wayne's parents were murdered, Bruce was cared for by Gordon, who was then a young street patrolman. The still photo of the young Bruce Wayne being held by an unseen policeman in the newspaper story that Vicki Vale and Alex Knox reads, is from that scene. Although discarded, the idea was re-used for the re-boot film, Batman Begins with Gary Oldman as Gordon. Also, the idea of this fateful meeting between Gordon and the future Batman has been incorporated into the DC Comic series to further explain the alliance between Gordon and Batman.
Patsy Kensit auditioned for the role of Vicki Vale.
In the film Jack Napier, The Joker, is the murderer of Batman's parents. One of the facts not addressed in the film that has its roots in the comic is that Batman would dream whichever villain he was chasing at the time was the one who murdered his parents.
The character of Alexander Knox (Robert Wuhl) was a character created for the movie. In the script the character was killed during the parade scene. In an interview with Starlog Magazine done at the time, Wuhl joked that his character should become Robin in the sequel.
A scene was cut from the parade sequence (but made it in the comic book version of the script) where the crowd discovered that all the money that the Joker was handing out was counterfeit. In a follow-up to the Joker's earlier line that he wanted "My face on the one-dollar bill," all the dollar bills that were thrown to the crowd had the Joker's picture in place of George Washington's.
In an interview with About.com, Christopher Nolan (director of Batman Begins and The Dark Knight) described this film as "...a brilliant film, visionary and extraordinarily idiosyncratic...". (Even Nolan appreciates and likes this film. So all this fanboy craziness over which Batfilm is better is even more pointless.)