Continuity mistake: When Lloyd is swinging his arms in the van, pretending to be 'running at an incredible rate', they are driving through a countryside with nothing but open plains. In the next shot, when Lloyd says 'we're really doing it though aren't we buddy?', look outside the passenger window. They are suddenly driving past houses in a residential area.
Continuity mistake: When Mary's family is shown in their home in Aspen. Mary is sitting on the couch with hot chocolate in hand, and is shown with her right leg crossed over her left. However, when Nicholas walks in, magically Mary's left leg is crossed over her right. (00:29:27)
Continuity mistake: In the scene at the truck stop, just before C-Bass comes over to Jim Carrey and Jeff Daniel's table, the same teenage boy walks by the window twice with his girlfriend. Also, the "Aspen" hotel is really The Stanley Hotel in Estes Park, Colorado. The Stanley is the hotel Stephen King based The Shining on. (00:22:00)
Continuity mistake: In the scene when Harry stops and says to Lloyd,"look at the butt on that", there is a man with a blue coat that walks behind them into a store. When Harry and Lloyd turn around to keep walking, you can see the blue coat man entering the store once again. You may have to freeze frame it to see the man the second time. (00:57:45)
Continuity mistake: When Harry sits down on the toilet and lifts up his legs, his eyes are closed, and they remain closed until the very end of that particular shot. Then, when it switches to the front shot of Harry a few second later, his eyes are open, right from the very beginning of that shot. And if you look closely at that shot change, you don't see Harry do the action of opening his eyes - they just change instantly between the shots.
Continuity mistake: In the Unrated Version DVD, in the van sequence after Lloyd's second encounter with Seabass in the restroom, Harry says that he will stop talking about Lloyd's encounter with Seabass. Lloyd turns his head and looks over at Harry. Then it switches to a close-up on Lloyd from the other side, and we see him repeat the same action of turning his head and looking at Harry, this time more sharply.
Continuity mistake: Lloyd reads the article about Mary and can't even pronounce the word "the", yet when Harry says look on the briefcase for her name, he says "Samsonite" with no problems, and Lloyd can easily read the "Man Walks On The Moon" newspaper headline in the hotel bar.
Continuity mistake: In the scene where Lloyd is making drinks for him and Harry, there is a half full bottle with something that looks like whisky in it. Then the cameras changes angle to Harry for 2 seconds, and then again back to Lloyd, but suddenly there isn't half as much "whisky" in the bottle as before. It is impossible that Lloyd could have poured so much "whisky" into the glasses in only 2 seconds. (01:19:40)