During the cartoon portions of the Super Mario Bros. show, watch the characters' lips carefully. If the character who is currently speaking is off-screen, and a non-speaking character is on-screen, the non-speaking character's lips will move as if it is the one who is talking, even when this is clearly not the case. Whoever was in charge of the cartoon's lipsynching clearly had no clue what they were doing, but the Director of Continuity (assuming the show even had one) really should have picked this up.

This may seem like a normal, acceptable messup for a cartoon, but it's not, as this happened in EVERY SINGLE EPISODE of the show!