Continuity mistake: In Season 2 Episode 22, Model Behavior, Woody has gotten his braces off. However, in this episode, he has braces back on again.
Land of Hold/Penny Henny - S2-E17
Deliberate mistake: When Garfield brings Jon to the broken TV, the scene's animation is still unrendered. (00:01:04)
A Remedy To Cure All Ills - S1-E6
Character mistake: King Uther calls the Lady Morgana, Morgause. (00:11:50)
Triumvirate of Terror! - S3-E8
Continuity mistake: When Joker zaps Wonder Woman and her mother, they are both standing in front of their thrones and fall forwards. But when Wonder Woman stands back up, her mother, still unconscious, is suddenly off to the side and behind the thrones. (00:11:35)