Continuity mistake: When Scooby puts down all the stuff he found in Wickle's' manor and Shaggy says those are just stuff Scooby wants, the toilet brush is on the left for Shaggy and it's standing up. When Scooby picks it up, he picks it up from Shaggy's left side, while it is slightly lying down. (00:21:25)
Revealing mistake: When Fred rushes in to fight the Black Knight Ghost in Mr. Wickles' castle, he is hit in the face several times with the back of his shield. As he falls, you can see the pad on the back of the shield to protect his face. (It is not noticeable when he first runs in.) (00:23:20)
Continuity mistake: When Shaggy gets out of the car on the red carpet, he has a drink in his hand with a straw, but when Scooby drinks out of the cup there is no straw. (00:02:30)
Answer: Yes! There was a real Heather Jasper Howe! Like the fake Heather Jasper Howe's True Identity is Jonathan Jacobo! He was arrested with Ned.