The Case of the Fickle Filly - S6-E11
Other mistake: George Tabor parts his hair on his right side, however when Perry cross examines Mr. Tabor his hair is parted on his left and then reverts back to his right side. The two dots on his tie are one low and one high, they also switch. The negative must have been flipped.
Other mistake: As the 2 buffaloes are walking out of the scene at the top of the hill Charlie says to Clyde that 'it's either gonna be her or me' but as both buffaloes' bellies are exposed in the same shot, it's clear that both buffaloes are males, or bulls.