Blocked Off - S1-E6
Other mistake: Masaru apologizes for the blunder (he butted heads with a teammate). Tsubasa cheers the rest of the team; look at the goalkeeper. He's wearing the same uniform as the rest of the players instead of his red jersey. (00:08:05)
Other mistake: When Teela is at Snake Mountain, she overhears TrapJaw saying how Skeletor's electrical creature will control all of the machines at the palace. When Teela returns to He-Man, she says that the creature Skeletor created is called Byte. There's no way for Teela to know the name of the creature, since TrapJaw never referred to it by name. (00:14:24 - 00:15:20)