Revealing mistake: When Josh is telling Drake that Mindy told him she loves him and when Josh slaps Drake near the end of the scene, it is really obvious that Josh is slapping air. His hand is at least 6 inches away from Drake's head and yet they play the sound effect for a slap.
Revealing mistake: Season 2, episode 2 "Virtu-Date": When Pim is jumping rope with the girl, she is building a card house. When she jumps you can see the tape holding it together.
Berry Scary - S1-E7
Revealing mistake: Blue is walking down a hall with a paddle ball in his hand. He is twirling around the ball and string around the paddle. However it's obvious that the string is somehow just passing through the paddle itself and not going around it. It's especially noticeable when he stops and the string slows down and visibly passes right through the wood of the paddle.