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)
Factual error: In the show Gaius wears glasses, except eyeglasses first came into use in the late 13th century while the legend of King Arthur is around the 5th or 6th century.
The Scorn of the Star Sapphire! - S3-E5
Continuity mistake: Right at the beginning, Batman and Steve are chained to some large rockets in a wide angle. it cuts to a closer shot and the rockets are suddenly much closer together. (00:00:10)