Revealing mistake: When the guy asks for a good shake and the weird kid shakes him you can see the people that work at the fast food restaurant moving back and forth very rapidly. This makes the shaking scene an obvious rewind and playback sequence.
Continuity mistake: In the scene when Dexter and Ed are thrown into the cushioned room in the insane asylum, Ed's hands are not handcuffed. The camera then shows Dexter and Ed says to look what he can do. As he is jumping off the wall you can see that his hands are handcuffed. The next time it shows Ed jumping, his hands are not handcuffed anymore.
Continuity mistake: As Mr. Bailey brings back a Mondo Burger, Spatch picks it up with a spatula. The close up scene shows the spatula bending. Not only should the burger have fallen off, as Spatch throws the spatula back down, the spatula is straight again as he grunts off.