When Shaggy and Scooby are shaking when they're afraid to exit the Mystery Machine, Shaggy is holding onto Scooby. In the shot when Shaggy tells Velma that they're not just going to sit before he and Scooby jump into the back of the Mystery Machine, Shaggy's right arm is around Scooby.
When Shaggy and Scooby are shaking when Velma asks them if they plan to stay outside when they arrive at the mansion, Shaggy's right hand changes colors from white to brown in some of the frames.
When the Specter dropped down a wipe for Shaggy, he was two stories higher than him and Scooby, but they were assigned on the nineteenth and twentieth floors and they were the highest floors.
When Shaggy turned himself and Scooby into monsters, it is surprising that they didn't scare each other by accident.
When the Spectre runs out of the bakery with the telescopic lens, he is shown to have both his hands out as he runs, neither of which are holding the lens. So how did he escape with it?