This movie was originally titled "Slammer" until Madonna wrote "Who's That Girl" and decided to use it as the theme song. The song went to #1 on the Billboard chart in August 1987.
Originally, Sean Penn was set to co-star with Madonna. After Shanghai Surprise (1986) flopped, the producers opted to go with Griffin Dunne, fresh from his success with After Hours (1985).
Oscar nominated Stanley Tucci appears briefly as a Dock Worker at the start of the film. This was his first credit in a feature film. Even in this brief shot, his voice is unmistakable.
During the development of the opening titles, Madonna asked Director James Foley if they could have a cartoon figure of her character introducing the credits. Foley liked the idea, and Warner enlisted cartoonist April March to create the cartoon.
Regarding Madonna's acting abilities, Director James Foley said she was very uptight and into every detail. "That's probably why it wasn't so good. In Desperately Seeking Susan (1985), when she didn't know what she was doing, she was being natural and at her best."