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: 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.
Trivia: During filming, John Leguizamo bought a Siberian Husky dog. Guess what he named him? Luigi.
Trivia: 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.
Trivia: Early drafts of the script reportedly followed the storyline of the video-games more closely, but for whatever reason these drafts were passed on to give the film an original storyline.
Trivia: Years after the film came out, co-star Dennis Hopper's son asked his dad why he was in the film, given its notoriously poor reception from critics and fans. Hopper, a working actor, responded with "So we could have money to buy you shoes." His son then quipped back "Dad, I don't need shoes that badly."
Trivia: Michael Keaton and Arnold Schwarzenegger were reportedly both considered for the role of Koopa, but both turned it down.
Trivia: Directors Rocky Morton and Annabel Jankel were reportedly widely despised by the cast and crew, who found them arrogant, difficult and unpleasant. Morton reportedly once even poured scalding hot coffee on an extra, burning them, because he wanted their costume to look dirtier. It came to a head one day when co-star Dennis Hopper had enough of their attitude and spent over three hours screaming at Morton and Jankel, berating them over and over and refusing to shoot his scene.
Trivia: Among the actors considered for the role of Mario were Danny DeVito and Tom Hanks. DeVito was reportedly interested but wouldn't commit as no script had been written yet. And Hanks was also interested, but was considered a risk at the time due to several high-profile flops, so he was taken off the project.
Trivia: Harold Ramis, a fan of the video-games, was originally interested in writing and directing, but a deal was never reached.
Trivia: The film went notoriously over schedule and over budget. For example, Dennis Hopper was only supposed to be on-set for five weeks... but due to production troubles, he ended up being on-set over fourteen weeks.
Trivia: Stars Bob Hoskins, John Leguizamo and Dennis Hopper were reportedly all furious while making the movie, as the script was constantly being changed (to the point it bore no resemblance to the one they signed up for) and the two directors were reportedly extremely difficult to work with. Hoskins and Leguizamo reportedly combated their fury by often getting very, very drunk during filming.
Trivia: Barry Morrow, the writer of "Rain Man," wrote a draft for the film that went unused. It was noted that his draft strayed very far from the source material, and was reportedly a low-key drama about the relationship between the two brothers that was described as being very much like his script for "Rain Man." When producers asked him to write a more adventurous script like the video-games, he refused, and was booted from the project.