When Shaggy and Scooby are gulping after being told they're going in the castle, Shaggy has no arms. This is also seen during The Scooby-Doo Show opening sequence.
When Shaggy and Scooby are scared by their shadows, the shadows are trembling, and there is a trembling sound heard, but Shaggy and Scooby are both perfectly still.
No water actually comes out of the canister that Shaggy drinks from that appeared after he called out for a drink of water.
How did Shaggy and Scooby not notice how they were clearly NOT being sawn in half?