Goofs

After Velma looses her glasses, the knight trips over her and lands in the guillotine. She mistakes the knights' growls for Shaggy's sore throat, and is about ready to give the knight cough syrup. Shaggy enters and takes the dose of cough syrup. However, when we see Velma's face immediately afterward, she is wearing glasses again.

When Daphne suggests leaving the painting room through another door, the Black Knight appears behind her and he has the red crest of hair on his helmet. The scene cuts to commercial, then it comes back on the same scene and the red crest is missing. It is still missing when he chases the gang away from the door, but then it reappears when he punches through the picture at Shaggy.

The very first moment in the Scooby-Doo franchise is met with a continuity error. In the very first shot of the episode, the viewer can see the truck on the screen coming towards them. When the truck gets closer to where the viewer can see inside it, there is no one in the driver's seat. In the very next shot, Professor Hyde-White is seen driving the truck.