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: When Mr. Fong and his henchman are arrested at the end of the episode, you can see Mr. Fong's Zen Tuo costume is white, but later on in the scene, it turns black.
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.
Continuity mistake: When Scooby slides out of the Mystery Machine during the chase scene, he stops at a pier and you can see there is a brick wall behind him, but when we see Scooby in the next shot, the wall has disappeared.
Chosen answer: A ghost wouldn't have to keep any food in the fridge - they don't need to eat. So it is one thing that proves the ghost is not a ghost.