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").

Near the end of the movie when the Bob-omb is walking upsidedown, look at its feet during the close-up. There is a Reebok symbol and the English flag.

During filming, John Leguizamo bought a Siberian Husky dog. Guess what he named him? Luigi.

A rather odd piece of trivia. The entire plot of the movie was original, and follows none of the video-games in the series. The actual games take place in the "Mushroom Kingdom", a fantasy world filled with fantasy characters. But for some reason, the movie takes place in our world, with alternate universes and sci-fi creatures. Many fans of the games were dissapointed that the filmmakers did no justice at all to the games.

Mario never says Daisy's name throughout the entire film.

Keep watching after the end credits. There is a short video where two japanese video game makers ask Iggy and Spike what video game they would like based on them. They both come up with 'The Super Koopa Cousins.'

By their enemies, the Mario Bros. are referred to only as mammals, monkeys and plumbers. They never say their real names.