Continuity mistake: In "Krusty Gets Busted", Krusty's natural skin colour is established as yellow. In "Brush With Greatness" we see him wiping off the clown makeup to reveal that he has yellow skin. But in "Homer's Triple Bypass", he comes to visit Homer, with his white clown face, and tells him that "this isn't make-up". Other episodes after that also show that his skin is white.
Continuity mistake: When the burglar points the gun at Apu and says "Hand over all your money in a paper bag" Apu immediately replies "Yes, yes, I will". But when Bart sees this incident on TV later, the time between the burglar demanding the money and Apu replying "Yes, yes" is much longer.
Continuity mistake: When the store is being robbed, Homer throws his bag to the side and it lands face down near the stand of chips Homer jumps into. But when they are watching the video of this incident later, the bag is standing upright, far away from the spot it previously was at.