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.
Other mistake: At the start of the film when Lloyd pulls up next to the Austrian woman, despite being tinted we can see through the limo's window. We don't see Lloyd climbing from the front to the back of the car, nor do we see the car rocking slightly which it would have done if someone was moving around inside. It's also impossible for him to get from the front to the back of the car in the time given.
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: Speaking of the airbag mistake, how about the fact that the hub of the steering wheel in the Cadillac Limo was small, and could no way have an air bag behind it? (00:08:40)
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)
Continuity mistake: There is a scene just after Lloyd meets Beth in the bar when Mary is skiing along and looks around for Harry who is still stuck on the ski lift. The shot is comprised of a long shot of her skiing to a grey marker and then a close up of her stopping and looking around. It is obvious in the shot when she comes up to the marker that the woman on the skis has much darker hair than Mary and is her "ski double". (01:13:20)
Continuity mistake: When Harry and Mary go out on the date to the ski resort, they get into a snowball fight. When Harry is shoving her face in the snow, the first time it shows Mary she is facing one way, but when they show her again she is facing a different way. In addition to this before the camera cuts to a different angle on Harry you can see Mary's nose is bleeding immediately after she stands up. The camera then cuts to a different angle and it isn't. (01:18:21)
Plot hole: By the time Lloyd gets to the airbridge the plane had already left. The finalisation of the boarding process after last call, plus push back takes at least 15 minutes. Lloyd would have easily caught up to Mary or the plane would have still been there.