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 Dum-Dum cuts the rope releasing Chug-a-Boom from the balloon, we cut to the car and you can see Clyde and Dum-Dum are surrounded by the rest of the Ant Hill Mob, but when we see the two in the next shot, the other members are nowhere to be seen.