Continuity mistake: When the Witch Doctor opens the crate and Scooby walks out, you can see the dog tag on Scooby's collar has nothing on it, but in the next shot the letters "SD" have appeared.
Continuity mistake: When Shaggy is telling Fred about his encounter with the Ghost of Geronimo, look at the Mystery Machine behind them and you can see the additional equipment is missing.
Continuity mistake: When Shaggy takes off his bowler hat to catch the flying garbage, the spots on Scooby-Doo's back are missing.
Continuity mistake: When Fred and Daphne arrive at a temple screen, the top lavender strip on Daphne's skirt is missing.
Continuity mistake: When we see Fred holding the picture of Champion in the Mystery Machine, he is holding one sheet of paper. When we see a full view of the gang in the next shot, Fred is now holding two sheets.
Continuity mistake: When Scooby is in Buck Masters' office, he sees a pointer dog on top of a stand and then does an impression of it by pointing his finger and freezes. When the camera closes in on Scooby in the next shot, the stand has disappeared.
Continuity mistake: When Scooby Doo rushes back on to the beach and Shaggy asks him, "What's with you?", Scooby's eyebrows disappear briefly.
Continuity mistake: In the shot of Scooby Doo turning on the radio at the beach, his spots are missing.
Continuity mistake: When the Mystery Machine is driving down Beach Boulevard, you can see Fred and Daphne are sitting in the front seat. When Velma locates Scooby-Doo on the radar using the transmitter in his collar, we cut to the Mystery Machine and Fred and Daphne have now gone.
Continuity mistake: When Scooby is looking for the rabbit in the magician's hat, the position of Scooby's fingers on the rim of the hat change between shots.
Continuity mistake: Scooby uses a magic wand to produce some flowers from the magician's hat, and he is holding the wand in his right hand when the flowers appear. When he is soaked by the flowers, he raises his right hand but the wand is nowhere to be seen.
Continuity mistake: When Fred says "We've lost him", Shaggy says "Groovy." His eyes then disappear.
Continuity mistake: When Scooby lands on the Phantom, the Phantom has nothing on his hands. When we see him talking to Fred a little later on, he is now wearing green gloves.
Continuity mistake: When Scooby lands on the Phantom, the gang cheer and Daphne and Velma are between Fred and Shaggy. In the next shot, we see Daphne and Velma, but Fred and Shaggy have disappeared.
Continuity mistake: When Daphne picks up the large key, there is a chest of drawers behind her that disappears when we see a close-up of the key.
Continuity mistake: When the gang are walking along in the castle, in a close-up of Velma and Daphne walking in the background a knight's armour and a shield, but when Daphne falls through the trap door, both the armour and shield disappear.
Continuity mistake: When Fred, Velma, Shaggy and Scooby discover that Daphne has fallen through the trap door, look at Shaggy and there is nothing on the wall, but when we see Shaggy scared by the ghost, a shield has suddenly appeared.
Continuity mistake: When the ham sandwich floats down in front of Shaggy, the sandwich has lettuce in the middle. When we see the sandwich on the table, the lettuce has gone.
Continuity mistake: After Scooby reads "Danger - Leave Haunted Isle" on the back of the map which Fred is looking at, he turns the map around and on the front there is an outline of an island. In the next shot, the outline has disappeared.
Continuity mistake: When Daphne is holding the large key, the rims on her cuffs are violet, but in a close-up, they are white.
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.