In Rachel Sweet's title song "Hairspray", Deborah Harry has an uncredited verse in the song. When Sweet sings "Hey girl, what you doing over there?", Harry sings the response "Can't you see? I'm spraying my hair!"
A scene was filmed where Tracey finds cockroaches in her hair. It was based on an urban legend about a girl whose brain is eaten by cockroaches that were living in her beehive hairdo. While it never made it into the final cut, it explains all the references to roaches in the latter part of the film.
The role of Edna Turnblad was originally written for famed transsexual Christine Jorgensen. However, when the role of Tracy had to be rewritten, John Waters also rewrote the role of Edna in order to keep his friend and muse Divine in the production.
There was a scene filmed, but cut, where, prior to her Corny Collins audition, Tracy breaks into Amber's house, destroys Amber's room, and dyes her hair blonde. This scene explains why Tracy's hair changes from brown to blonde between scenes.