Continuity: While on the ledge just before entering the alternate dimension, the Mario brothers switch places.
Audio/visual unsynchronized: At the ledge just before they enter the alternate dimension, you can hear the words "Watch it!" as Mario and Luigi switch places. It's obviously Mario speaking, but if you look, he isn't.
Continuity: The Mario brothers appear momentarily without their tool belts after they first enter the alternate dimension.
Continuity: When the Mario Brothers are in jail, the position of Toad's arms change between different shots from his wrists to his shoulders.
Continuity: In Devo 4 Luigi's button unbuttons and rebuttons itself.
Factual errors: 191 X 191 = 36481, not 26481
Continuity: The glass that falls on the phone book as the Mario Brothers first arrive at the police station disappears in the next shot.
Continuity: When the Mario Bros. are in the elevator with the dancing Goombas, they are wearing their specialized jump boots. When they get out of the elevator, they are wearing their normal shoes.
Continuity: After the brothers steal a police car the text on the side is momentarily reversed, showing the shot was mirrored.
Continuity: When Leena steps on the Rock to keep it from falling through the grate, the length of cord that has fallen through the grate changes between shots.
Continuity: When the Bob-omb blows up under Koopa's legs, he flies into the air, and is shown shortly after falling straight down. But in the shot just after, he falls at an almost 45 degree angle into the suspended bucket.
Continuity: The lump of fungus seen in the final scenes that transforms into the King is much bigger than previously seen.
Continuity: When Koopa is talking to the cop about the Goomba's training with the hand-held Devo Guns, the Devo Gun in his hand vanishes between shots.
Factual errors: In the credits, Dan Castellaneta's name is misspelled (as "Castellenetta".)
Continuity: In several scenes, Koopa's Flamethrower type gun is scene without a flame which is revealed later in the movie to disable the gun. However the gun still fires and on close ups is scene with a flame.
Factual errors: In the scene where Mario and Luigi are being chased by the police, while they're side by side with them, Mario slams on the brakes. Later after that scene when they're going through the tunnel, he claims there are no brakes.