Continuity mistake: Rob, Laura, Buddy and Blacky are in Robs basement, there is no wine bar, or giant boulder, and the steps that come down from upstairs lead straight up to nowhere. Because there's a window to the left beside the steps, rather than how it was when they were buying the house where you could see into the house. And there's a giant gap under the wall behind the pool table. There's also a random door that leads somewhere also behind the pool table. (00:24:47)
Continuity mistake: When Laura tries to read the phone number that Rob scratched out, Rob gives her the number as "New Rochelle 69970," which happens to be the Petrie's own phone number, as noted in other episodes.
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.
Continuity mistake: When Rob is trying to draw the horse and accidentally draws on the wall, the drawing changes depending on the shot.
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.