Goodnight, Seattle: Part 1 - S11-E23
Continuity mistake: (This is for "Goodnight Seattle.") When Eddie is eating the pate with the ring in it, in the wide shot we see that he's finished all the food and is licking the plate clean. It then cuts to a closeup, and the plate is suddenly full of food. Back to the wide shot, and he's licking a clean plate again.
Chosen answer: The buffalo that later charges Smiles A Lot comes up and butts into the side of his horse, knocking it over. It can't clearly be seen because of the way the shots change, but that's what happens.