Continuity mistake: When Mario, Toad and Luigi are driving to the rebel fort, the seatbelts they are wearing disappear for most of the scene. (00:17:30 - 00:18:40)
Two Plumbers and a Baby - S1-E17
Continuity mistake: In one scene, Luigi is wearing the same color hat as Mario and when Luigi opens his mouth to talk, it's Mario's voice we hear.
Other mistake: On the "Mario's Greatest Movie Moments" DVD of this series, from the main menu, go into the trivia game. The fifth question asks you about the Super Mario Bros. Super Show episode 'Count Koopula.' It asks you "What's room number that the Mario Bros. were put into in Koopula's Castle?" It's supposed to say "What's THE room number that the Mario Bros. were put into in Koopula's Castle?"
Audio problem: When they are trying to escape Koopa and the little caveman speaks, then Luigi answers him, he has the Princess' voice.
Continuity mistake: When Toad screams and runs away after the Bob-omb lights, Mario, Luigi and their car disappear. (00:16:00)
Robo Koopa - S1-E52
Continuity mistake: When Luigi crawls out of the remains of the Plumbernator warsuit, his face is still in the unit of where it was when he was in it, even though he's outside of it right now. (00:11:40)
Other mistake: When Mario, Luigi and Toad are speeding to get to the rebel fort, Toad tells Mario to look out the car's rear-view mirror. However, the car doesn't have one. (00:18:15)
Robo Koopa - S1-E52
Continuity mistake: Near the end of the episode, when Koopa is tricked into pushing the ejector seat button, Bunsun has disappeared beside Dr. Nerdnik. (00:12:30)
Love 'Em and Leave 'Em - S1-E8
Continuity mistake: In the scene where the Princess first has the idea for getting another love potion, the spots on Toad's head change to black then back to red. (00:14:12)
Continuity mistake: When the Mario Bros. speed up their car to get to the rebel fort, in one shot both of Mario's hands are on the steering wheel, and in the next shot his right hand is on some sort of lever that makes the car go faster. Luigi's hands also change position in these shots. (00:17:45)
Robo Koopa - S1-E52
Plot hole: Near the end, Robo Koopa sets down Dr. Nerdnik after he had just captured and held him hostage. Why would he do that? (00:11:55)
Raiders of the Lost Mushroom - S1-E49
Continuity mistake: Near the end, when Koopa escapes through the warp you will see, for a split second, that Mario and Luigi have switched their colors. (00:38:15)
Continuity mistake: When Mario, Luigi and Toad say goodbye to the Princess, Toad is standing at the front of their car, Luigi in the middle, and Mario at the back. Two shots later, the order changes to Mario at the front, then Toad, and Luigi at the back of the car. (00:15:10)
Continuity mistake: The Thunderbirdo is supposed to be pink. It is green when first visible after Koopa orders it up. It turns green again right before it explodes. (00:19:15 - 00:23:55)
Continuity mistake: At the beginning of the episode, when Koopa's state Troopa makes the Mario gang pull over, both vehicles stop in the middle of the road. From there on, the cars are at the side of the road. (00:13:55 - 00:16:25)
Continuity mistake: After the Marios say goodbye to the Princess, Mario is at the front of their car, then Toad, and Luigi at the back. Mario and Luigi swap places for the rest of the scene. (00:15:15 - 00:16:10)
Other mistake: Koopa's army tries to stop the Marios from getting to the rebel fort by driving a truck and stopping it in the middle of the road. However, nobody is driving the truck. (00:18:25)
Raiders of the Lost Mushroom - S1-E49
Audio problem: When Mario picks up the Lost Mushroom for the first time, his mouth is moving, but not saying anything. (00:32:10)
Continuity mistake: When Koopa sends Mouser to hunt down the Marios after finding out they've escaped, the binoculars that he was holding have disappeared. (00:17:55)
Continuity mistake: As Mario, Luigi and Toad speed to the rebel fort, the side-view mirrors keep disappearing. (00:17:25 - 00:18:40)