Goofs

When the monsters take over the hotel, Daphne is wearing a purple v-neck dress and hides the Daemon Ritus in a simple purple handbag. When they wake up on the beach, she's wearing a light purple halter swimsuit and is carrying a light purple beaded handbag, and she never had time to change. When Fred's protoplasm head enters her, she is wearing her dress again.

When a Daphne-possessed Fred is going through the woods, he's carrying Daphne's purse. When the gang sees the Voodoo Maestro, neither Fred nor Daphne are carrying the purse.

When Shaggy is skateboarding, Scooby grabs the hook to save them from being squashed by the machine. Right after they jump off the skateboard you can see the skateboard fall off the conveyor belt. It then reappears on the belt a second later to be squished.

Daphne runs up the framed stairwell wearing tennis shoes instead of the pink go-go boots she wears throughout the rest of the movie. (See trivia.)

At the end when Daphne is fighting the wrestler, her black belt is on and off between shots.

When Velma falls while catching the Luna ghost and starts hanging, her skirt is stuck to her legs even though shes upside down. The character of Velma Dinkley is NOT a flip-skirt girl. So they taped the skirt to Linda Cardellini's legs to prevent Velma's revealing her underwear.

When Daphne, Shaggy, and Scooby are going into the castle, Daphne bribes Scooby with a Scooby Snack from her purse. When she was invited to Spooky Island, Daphne did not know that Scooby would be there. But Scooby Snacks are a popular treat which can apparently be bought at any vending station in the Scoobyverse.

At the beginning of the film when Shaggy and Scooby are in the barrel to run from the ghost, Matthew Lillard's real hair can be seen as his wig is blowing from all the air.

During the BBQ scene in the van, even with the roof vent open the van would be filled with thick toxic smoke. Also, the space in the scene is wider than the space in the back of a van.

When Scooby is pushing the cart of luggage with the gang on it, a pulley system is clearly seen pulling the cart. This cord disappears and appears randomly throughout the scene.

When Shaggy and Scooby are being picked up by the plastic sausages during the ride, you can clearly see strings moving the sausages.

In the opening scene where Daphne has been captured by the Luna Ghost we can distinctly hear her shouting for help and complaining about the ghost grabbing her. This is almost immediately prior to her release and the unmasking of the Ghost. She says later on that she was captured for nearly an hour and a half but about the time Fred tries to use the hose and gets knocked over, we see Daphne has been gagged with her own scarf so how could she speak earlier?

Reflection of light panels in Velma's glasses at the beginning as the gang is breaking up.