It May Look Like a Walnut! - S2-E20
Character mistake: Rob is having a nightmare, part of which involves the disappearance of his thumbs. When he finds Laura at home, the script calls for him to say, "I want you to help me get my thumbs back," but he actually says, "I want you to help me get my thumb backs." His thumbs are also still there but hidden (you can see a portion of them in one frame of the episode).
It May Look Like a Walnut! - S2-E20
Continuity mistake: The episode opens with Rob watching a horror movie on television. The bedside clock shows the time as 9:05. At the end of the episode 23 minutes later, the clock shows 9:10.