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.
Don't Trip Over That Mountain - S2-E22
Character mistake: Laura tells Millie that the phone rang 6 times. The phone actually rang 7 times.
Continuity mistake: When Rob is trying to draw the horse and accidentally draws on the wall, the drawing changes depending on the shot.
A Surprise Surprise Is a Surprise - S2-E30
Factual error: Buddy asked Sally "why haven't you had a birthday...?" Yet a few episodes ago (Season 1 Episode "Where you been, Fassbinder?") Sally had a birthday she cried and cried. Buddy and Pickles, Rob and Laura were all there.
When a Bowling Pin Talks, Listen - S2-E32
Continuity mistake: Buddy poked the punching bag with Mel's face on it. Then later Mel comes in when the delivery service guy comes. Mel's face is aiming towards the wall. His face on the punching bag keeps appearing and disappearing every time we jump cut from the writers and the delivery guy.