Continuity mistake: Near the end, during the scene where Vince Vaughn is standing on the table at the pancake house, the camera cuts to John, and you can see Vince in the windows, with his shirt off, swinging it over his head. The camera cuts back to Vince, and his shirt is still on, THEN he takes it off & swings it around. (01:26:40)
Continuity mistake: Check out the scene with Mikey and T in Vegas ordering breakfast. In the medium and long shots they toke on some big cigars creating a good amount of smoke - on the tighter shots there's no cigars and no smoke. (00:18:15)
Continuity mistake: Toward the end when Mike is pinning the card with Lorraine's number to the calendar, he pins it on a Saturday and starts to draw a red X through Wednesday, leaving two blank days between. Switch to a close-up shot and he's penning the X with one blank day until the card. Switch back to the long shot and you can again see two days between the X and the card.
Continuity mistake: During the hysterical Sega hockey scene, watch the score and time remaining in the game as they show the TV. The score goes from 9-5, to 3-1, to 8-5 all in the same continuous game.
Continuity mistake: In the scene where Ron goes into Mike's house after calling Nikki, Ron sits on a chair in front of Mike. In the frontal shots, Ron sits with his legs crossed. In the shots from behind, he sits with his legs apart. There's not time between shots for Ron to cross and uncross his legs. (01:06:30)
Continuity mistake: At the end when Trent and Mike are sitting eating breakfast and Trent thinks a girl is flirting with him. He picks up a napkin to play peek-a-boo. When we switch to the shot of the girl his hands are holding nothing. Then we go back to the shot of him his napkin is there again. (01:33:20)
Continuity mistake: The scene where the guys go into the swingers bar. By jumping the queue, they go through the back entrance through the kitchen. As they go up the stairs, the shadow of the cameraman is also seen following the group.
Continuity mistake: In the scene where Mike and Trent arrive in Las Vegas, they pull their car into the Stardust, which is located on the strip, hand the keys over to the valet and walk into the casino. The next shot shows Mike and Trent in the casino, only they are now inside the Fremont which is located downtown. You can tell they are at the Fremont while Mike and T are at the blackjack table. Fremont is spelled across the felt and when the dealer flips his hole card, his top card reads Fremont Casino.