Citizen Toxie is full of cameos, including Stan Lee, Corey Feldman, James Gunn and Lemmy. Also, Ron Jeremy plays the mayor (and SCREW Magazine publisher Al Goldstein plays his lackey).
Eli Roth appears in a blink-and-you-miss-it cameo in Toxie.
Our Lawyers Advised This Trope: An early teaser trailer for Citizen Toxie included Hugh Hefner loudly declaring "Only The Toxic Avenger knows for sure!". Although Troma was given permission to film at the Playboy mansion, Hefner never gave them permission to use the Playboy name nor his likeness, and a cease-and-desist letter caused Hefner to be purged from all subsequent trailers and the film proper.
Too Soon: Awesomely averted. Citizen Toxie was released in the States shortly after the events of September 11th. While most films underwent editing to remove images of the Trade Center, Citizen Toxie didn't. It received a standing ovation from a New York audience for this.