Continuity mistake: Scooby finds a clump of ape hair stuck in the wine cask. It cuts to the gang, then back to the cask as they walk up and suddenly the clump of hair is twice as thick. (00:16:45)
Don't Fool With a Phantom - S2-E8
Continuity mistake: The gang find Jonny tied up in a chair and he says it wasn't a publicity stunt. Both his arms are tied up to his sides by the rope. It cuts from the close up to show them all again, and suddenly Jonny is holding his hand to his head and Fred is suddenly pulling on the rope, his arm outside of the rope. (00:02:45)
Revealing mistake: After Mr. Maxwell says that the local people refuse to work on the movie, Velma asks why. In her close up, her right pupil is horribly misshapen. Not round, but a wobbly, almost cloud like shape. (00:01:35)
Continuity mistake: Just before Shaggy goes into the secret passage way, he sits on a stone, and his hair has somehow turned yellow.
Continuity mistake: When the gang 1st arrives at the beach. Fred stops the Mystery Machine. Although the van is stopped. The next shot shows Fred still sitting at the wheel, turning it, as if he is steering.
Don't Fool With a Phantom - S2-E8
Other mistake: When the wax phantom appears behind Scooby and Shaggy the man who supposedly is impersonating him in the suit is in clear sight directly behind Fred Daphne and Velma.
Don't Fool With a Phantom - S2-E8
Continuity mistake: When the door to Mr. Grisby's house opens, Shaggy and Scooby have their back to it with Shaggy holding Scooby's head. It cuts to a different angle, and instantly Shaggy has let go of Scooby and they are facing the door. (00:05:10)
Continuity mistake: The gang emerge from the secret tunnel and find the movie crew dressing rooms. It shows one, then cuts back to the gang. Then it cuts back and suddenly another dressing room trailer appears next to the one seen moments before. (00:17:20)
Jeepers It's the Creeper - S2-E3
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.
Don't Fool With a Phantom - S2-E8
Revealing mistake: When Fred makes a joke about the dummies at the end of the episode, Daphne doesn't have a neck. (00:20:55)
Don't Fool With a Phantom - S2-E8
Continuity mistake: Velma gets mad and stomps her foot, activating a secret switch. The floor is made of square and rectangular stones. The angle changes to show her Fred and Daphne, and suddenly the stones are of random organic shapes. (00:12:50)
What a Night for a Knight - S1-E1
Plot hole: It seems unlikely that: 1. The curator, who's short and chubby could fit into that suit of armor. 2. How he could be strong enough to lift up the table Scooby and Shaggy are hiding under at one point, 3. That the museum has no security guards who might catch the curator and his thugs during their art forgery scheme and 4. There are eyes shown moving in the suit of armor when the gang's talking to the curator despite the fact he's the Black Knight Ghost.
Scooby-Doo and a Mummy Too! - S1-E12
Plot hole: If the guilty man knew the diamond scarab was in the hippo statue then there's no reason he couldn't have broken the statue open and taken it.
Continuity mistake: The Snow Ghost's mask goes from being a hood type to just covering the guy's face in one shot when he's stuck in the snow.
Mine Your Own Business - S1-E4
Other mistake: When Daphne falls down the mine shaft, Fred has turned his head around his body 180°.
A Night of Fright is No Delight - S1-E16
Revealing mistake: When Scooby and Shaggy are on the bicycle with the Green Ghosts, the Ghosts' chains are missing.
A Night of Fright is No Delight - S1-E16
Other mistake: Velma asks Shaggy "How'd you get that green stuff on your hands?" but there is no visible "green stuff."
A Night of Fright is No Delight - S1-E16
Revealing mistake: When Scooby, Shaggy and Velma are on the drainpipe, it breaks and throws them into a cave. But the drainpipe hits the ocean like it is glass.
Other mistake: When the gang are swimming, a plant in the foreground moves along with them.
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.