Other mistake: You have to know Colorado to get this one, but the two guys are on a trip to Aspen to return the suitcase to the woman. But when they finally arrive, they are not actually in Aspen like you are supposed to assume they are. The whole Aspen scenario actually takes place in Breckenridge ski resort. (00:54:10)
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: 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: 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)
Revealing mistake: At the Swanson's ski-lodge, there is snow on the rail of the balcony, but the mountains in the background are completely snowless. (00:29:27)
Plot hole: After Lloyd's encounter with Seabass in the restroom at the gas station, we see the FBI waiting for Harry and Lloyd at the Colorado border (we even see a front shot of the road and mileage sign), and there is no town in sight. Then we see Harry and Lloyd 3 miles from the border, driving toward it, where the FBI are waiting. Then we see Lloyd coming out of a market in a little town, after which, upon leaving the town, he drives in the wrong direction. How did they suddenly come upon this little town, especially when they were only 3 miles from the border? Did they turn around, or what happened? (In the unrated version, the van scene 3 miles from the border is extended, and it seems that they would have reached the border, and the FBI, by now.) The whole scene here is pretty confusing.
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.