Continuity mistake: To catch Ripley, Fred uses the remote to bring the draw bridge up. But Ripley manages to scale the bridge before it gets all the way up and falls into the moat below. As he surfaces, the draw bridge is instantly and suddenly down all the way again as the gang rush out onto it.
Continuity mistake: When the Gladiator Zombie is chasing the Mystery Gang in the golf cart, he flicks his whip at them. Scooby is seen on the left side of the back seat looking out and covers his eyes. The very next shot, Scooby is suddenly on the right side of the seat looking forward.
Continuity mistake: The gang investigates the trail of limestone to a manhole in the middle of the street, with nothing around it. But when Daphne is putting on her "Wallowing galoshes" boots, somehow a small brick wall just materializes in the middle of the street for her to sit on - and then vanishes a couple shots later. Not just the fact that it appears and vanishes between shots, but that there is a random brick wall in the middle of the road.
Continuity mistake: Lysander digs through the box of jewelry frantically trying to find the medallion that was slapped away from him. After the merchant says he sold it to Shaggy, the box is shown again and the arraignment of the jewelry changes back to about how it was before he dug through it.
Continuity mistake: As the camera pans down to show a Greek play being staged, the two figures in the center of the stage have their backs to the audience. It cuts to show the gang in the front row and suddenly the guy shown is facing the audience.
Continuity mistake: When the gang gets to Santorini, the centaur shows up again and they take off to the right following the wall. Then the 'old maniac Moped guy' comes at them from the right going left. So they are going right, the Centaur is behind them to the left, and the Moped guy is to the right. So they go into a doorway between them. The Moped guy comes from the right and goes to follow, then suddenly the Centaur comes from the right also, when he was on the left.
Continuity mistake: Velma and Daphne are sitting on a bench, with Velma on the left and Daphne on the right. When they hear Shaggy and Scooby screaming they quickly stand up and the shot changes to show them running past the girls. The bench they were sitting on vanishes, and the girls switch places.
Continuity mistake: As Scooby and Shaggy are locked up for stealing the frozen bananas, the lock is placed on their holder hanging down straight. A couple shots later, it is now hanging out to the side and is smaller, most noticeably the lock hole is smaller. The lock hole also changes what side it is on.
Continuity mistake: After the people start running away when the dragon arrives, Shaggy and Scooby are shown still locked up and the food splatters on their holders are there. A couple shots later, the food splats change around in position and color. And then moments later, the food vanishes from the wood all together.
Continuity mistake: When Fred walks up to Excalibur, the design is different than when seen later after Shaggy and Scooby are scared by the dragon. The blade has designs on it, including a gold and green diamond shape, and the hand guard is curved. And the handle is wavy, with the end of it being a gray cone shape. Then after Scooby and Shaggy come running, it is shown again. Only now the shape of the blade is different, the gold and green diamond part have vanished, the hand guard is now just straight, the handle is not wavy, and the gray cone at the end has turned into a sphere.
Continuity mistake: After Daphne touches the dragon's tail, Shaggy and Scooby take off and run into one of those coffin like things with spikes on the inside for torture, to hide. As they go in, you can see the spikes on both sides, and there is nothing else in it. But when Shaggy turns on a flashlight, you can see the spikes to their back have vanished, and a skeleton appears.