Continuity mistake: When Wilby goes into his bedroom, he takes out his PJ's from the bureau drawer, leaving the drawer open. He goes into the bathroom to put on the PJ's. When he comes out of the bathroom, the drawer in the bureau is closed.
Continuity mistake: Dr. Kozak enters the lab when Shaggy has the blood tube, and his hands are at his side, but in the next shot, his hands are up by his face.
Continuity mistake: In the scene when Diane is talking to her husband in the office she slams two heavy books on the table and one slides off of the other, but then they show the books and they are piled neatly on the desk.
Answer: I assume this is merely a movie plot device so that the audience does not get confused when Wilbur is in his dog form or that the other characters are wondering why there are suddenly two identical dogs.
raywest