Trivia: At one point during the song "Jack's Lament", Jack pops up between two tombstones. The tombstone on the left is a figure from the painting "The Scream", and the tombstone on the right is the horse from Picasso's "Guernica".
Trivia: The portable devo guns Mario & Luigi use to turn Koopa into slime are actually Super Scopes, (used in the Super Nintendo Game "Super Scope"). They're kind of the Super Nintendo version of the Nintendo Zapper from "Duck Hunt" for NES (Nintendo Entertainment System").
Trivia: The man playing Joel Glicker's father is Barry Sonnenfeld, the film's director.
Trivia: The moths that fly out of Billy's mouth after he cuts the thread are real, the actor held them in there for the effect.
Trivia: Paul McGann plays both Girard (the man out to revenge his sister's honor) and the Cardinal's Guard who is killed by D'Artagnan out by the city ruins.
Trivia: When Chance jumps out of the car, he bangs the youngest child's head on the door hard enough to make the camera pan off him pretty fast.
Trivia: The film was released as "Dennis" in the United Kingdom in order to avoid confusion with the British comic strip character, "Dennis the Menace."