Director Frank Henenlotter admitted in an interview that he had to remove 11 pages of the script during filming because the producers decided to make the film less gory.
When the sheriff mentions Little Hal's gift of a remote-control lawn mower when talking to Uncle Hal, it is a reference to Frank Henenlotter 's previous film, Frankenhooker (1990), in which one of the main characters is killed in a freak accident involving a remote-control lawn mower in the opening scene.
Frank Henenlotter said that while filming the police chief's alliteration line ("Bailey, you book the Bradley boy", etc.) he had to leave the set because he was laughing so much.
According to Frank Henenlotter, the reason the effect where the police officer's eyes pop out while being strangled looks so ridiculous is that there was originally supposed to be blood gushing from the eyes and mouth, but it was removed after it was decided to make the film less gory. Thus, the effect was unfinished.
At one point during filming, the actress playing Brainia passed out from heat exhaustion because it was so hot inside the mask.