The original edit was over four hours long, so the Troma team split it into two films.
The scene where Toxie squashes a man's nose into a taiyaki was the first idea that Lloyd Kaufman came up with for the sequel, during his visit to Tokyo to promote his first film, The Toxic Avenger (1984).
Melvin's last name was changed from Ferd (as it was in the original) to Junko for the sequels, in order to explain his Japanese heritage for the plot of the movie.
John Altamura was fired during production (according to Lloyd Kaufman and Ron Fazio) for "abusing his authority". Ron Fazio, who plays an executive of Apocalypse Inc., was originally asked to only to be the Toxic Avenger's distant shot double. However, after Altamura's dismissal, Fazio was asked to play the part and provide the character's voice. The producers kept the scenes with John Altamura, hence both men are credited with the title role.