Continuity mistake: Scooby finds a clump of ape hair stuck in the wine cask. It cuts to the gang, then back to the cask as they walk up and suddenly the clump of hair is twice as thick. (00:16:45)
Continuity mistake: When Jimmy is turned into The Mechanical Boy, he is wearing a jacket but when he arrives at the cave, it's gone.
Continuity mistake: When Floris and Sindala ride out the gate by surprise, the cook's position (he was opening and closing the castle gate to let them through) is different when the camera changes.