On the Mighty Plumber show on TV when the woman picks up the phone to call Mighty Plumber, the phone is blue. In the close up when she makes the call, the phone's handset is gold. Then when she drops the phone, the phone is blue again.
When Mario and Luigi arrive at Pipe Land, Mario's hair is briefly incorrectly colored as black like in the first four episodes, instead of brown.
While King Koopa is having his tantrum at the beginning of the episode in his castle in Dark Land, the thick black line of the animation frame can be seen on the left.
When Mighty Plumber's rope grabs Cheatsy, the color of his head changes from green to his skin color, then back to green in the next shot.
When Koopa is walking up to his desk and tells Bully and Big Mouth he found the map so he can rob Pipe Land, Big Mouth's head is the same color as his skin instead of gray and Bully's head the same color as his skin instead of pink.
During the scene where King Koopa and Cheatsy are watching "Mighty plumber" show, the lady screams and the background behind her is the room King Koopa was previously having his tantrum.