Continuity: Captain Cutler shoots two harpoons with chains attached into the back doors of the Mystery Machine. The Mystery Machine tries to drive away, but Captain Cutler holds the chains to prevent their escape. Freddy then reverses and knocks Captain Cutler into the water. As the Mystery Machine drives off the chains and the harpoons have disappeared from both the inside and outside of the Mystery Machine.
Revealing mistakes: After Daphne gets blown up, the ground moves when she hits the ground, revealing that there's a crash mat there.
Continuity: When Shaggy is flexing his muscles the refrigerator door is open and he's standing right in front of it but in the next shot when he throws the potion that Scooby made, the door is closed and he's standing off to the side.
Continuity: When Fred is on the ground after being knocked off the motorbike during the joust with the Black Knight, he is still wearing the red neck scarf. When Daphne lands on the ground next to him, the red scarf is further away on the ground.
Continuity: When Velma lifts up the secret passageway, there isn't a green chip there. But then she just picks it off.
Revealing mistakes: In the 10,000 volt ghost and black knight scene, the explosion should have ruined the MYSTERY INC. car.
Continuity: After Daphne fights the 10,000 volt ghost and gets hit way over to where Fred is, her hair is singed on the ends (as it would be). But when she and Fred meet up with Velma, her hair is normal again.
Continuity: When the gang receives a fax on the results of the dinosaur scale, Velma takes it away from Shaggy and it appears that she is looking at one side of it. In the next shot the fax is turned the opposite way.
Continuity: During the fight between the Black Knight and Daphne in the Winkles Mansion, Daphne's shoes change. They start of as high heels, then they change to being flat and then with a slight heel all during the fight sequence.
Factual errors: When Velma is watching the projection in the cave, the projector has no tape on it. The wheels are also spinning the same way, so no projection would actually be shown.