Continuity mistake: Right after the car chase when the Mystery Machine crashes into the boat and fishes, when Scooby reaches into the pile of fishes, his arm turns green. When he pulls out the fish, his arm is back to normal. But when he reaches back down it changes to green then back to normal when he pulls out Shaggy.
Continuity mistake: During the chase scene, we see the Fisherman's Wharf sign and then cut to the Mystery Machine turning around a corner. At this point, you can see Scooby is in the vehicle with the rest of the gang, but just a few seconds later he is back on top of the Zombies' car.