When at Count Shockula's house, and at the beginning of the chase, the moon is crescent-shaped. However, once in the zoo, the moon is full.
While at the zoo, when the gang and monster first run past the ice cream cart, the cart does not have a shadow. A shadow suddenly appears beneath it just before Scooby walks up to it.
The news announcers in different scenes have different likenesses but the exact same voice.