The Catwoman from Channel Six - S2-E12
Continuity mistake: When Leonardo cuts off April's collar, she asks what happened, but instead of it being Leonardo standing there with the sword, it's Donatello with the sword.
Continuity mistake: When the Wooly What's-it releases the rock blocking the cave to Rainbow falls, the water splashes on the fobs. When they hop over and jump in, one of the fobs disappears and reappears.