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)
Revealing mistake: In the song "Living Island", we see Judy frog jumping over Pufnstuf. When she goes back down, the wires holding her up and putting her down are visible.
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.