Hugh Hefner was originally going to be in the Tromadu segment. A shot of him saying, "Only the Toxic Avenger knows for sure!" appears in the original teaser trailer. Unfortunately, a cease-and-desist order from Hefner's lawyers forced Troma to remove any and all visual depictions of him from both their advertising and the final film. By all accounts, Hefner himself was initially fine with being in the film, but his lawyers convinced him he was unfairly coerced into being in the movie. Because of this, during the "Special Thanks To" sequence of the final credits, there's a special "No thanks to Hugh Hefner, who asked to be cut out of this film" credit.
Before the film's world premiere, a decision was made to leave the World Trade Center in the opening narration despite the 9/11 attacks taking place a month earlier. This decision was applauded by the crowd.
Celeste Octavia (the gynecologist's nude nurse) offered to do her role completely nude in exchange for one line in the film, where she asks the doctor if it's time to remove the thermometer from her butt.
The narration in the beginning and the ending was by Stan Lee, who is credited as Peter Parker, the name of his comic book character (alter ego of Spider-Man).
The now classic stock footage of the car-flip stunt from Sgt. Kabukiman N.Y.P.D. (1990) is used once again for this film. This footage has also been used for several other films including Terror Firmer (1998), and Tromeo & Juliet (1996).
Lemmy: of the band Motörhead as an onlooker outside of the school. He says the line, "It's a shame that happening on Take a Mexican to Lunch Day and all."
Mitch Cohen: , who played Toxie in the original O Vingador Tóxico (1984), as a racist who is lynched by the KKK after Toxie gives him a black-face treatment with a car engine.
Eli Roth: The horror director is standing next to or behind Lemmy Kilmeister outside of the school in several scenes.