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.
Other mistake: There is a scene where the gang is the home of the Bank President, just after dropping off the injured bank guard. At one point the Bank President is standing behind an end table of some kind with a lamp on it. Even though there is nothing underneath the table to block your view you cannot see the lower part of the Bank President's leg. It looks like it has been cut off.
Continuity mistake: After the gang's encounter with the hermit they head back to the Mystery Machine, and when Fred opens the passenger door in the wideshot its colors are the usual blue, green, and orange, but in the closeups the door's exterior is solid green. The style of the door handle is also different in the closeups.
Continuity mistake: When the gang are standing by the well after Shaggy and Scooby told them they had seen a ghost, a rope on the spindle and the end of the rope is loose, but after Velma says that there are no such thing as a ghost, we cut back to the gang and the end of the rope is nowhere to be seen.