Revealing mistake: In the beginning of the film, Harry reaches for his radio after getting a call. The radio is not powered. You can see the display doesn't light up.
Continuity mistake: After Harry and Lloyd start gagging over the atomic peppers, we see a brief shot in which everyone else in the restaurant looks at them (and the waitress suddenly appears in that shot as well). But in very the next shot (back to Harry and Lloyd, still gagging), nobody is looking at them (and the waitress, who was there just a moment ago, disappears).
Visible crew/equipment: When they are riding the mini-bike as "Where I Find My Heaven" is playing, the camera goes towards the sky. Look to the far left, you see a small looking man in blue overhauls.
Continuity mistake: When the "gas man" falls to the floor due to the atomic peppers that Harry and Lloyd sneaked into his burger, Harry and Lloyd laugh at him, and Lloyd even points at him. Then he stops pointing at him and looks at Harry. But only a moment later, in the very beginning of the next shot (a close-up of Harry and Lloyd), Lloyd is instantly pointing again.
Continuity mistake: When Harry and Lloyd start singing "Mockingbird," we see a front shot of the "gas man" getting annoyed and gritting his teeth. Then it switches to a side shot, and his annoyed expression is now different, instantly.
Visible crew/equipment: When Jim Carrey slides in the airport to pick up the briefcase, he stops at a strip of red tape which marks the place where he should stand up.
Continuity mistake: When Lloyd drops Mary off at the airport, the interior of the car is different once Lloyd gets back in.
Suggested correction: The interior is the same, but looks different due to the direct sunlight in the first shot (blue instead of black). The only difference is the steering wheel, which is not contain the airbag on the way to the airport, but is totally different when Lloyd is back in the car and is driving right before the impact.
Revealing mistake: When Harry and Lloyd are reading the newspaper about the International Preservation Society, the exact same paragraphs are repeated many times throughout the paper.
Continuity mistake: Early in the movie when Lloyd gets his wallet trapped in the newspaper machine, it shows his wallet, however in the very next shot his wallet is not there.
Revealing mistake: When Lloyd comes back for Harry on the scooter, it has two small training wheels on the back. They disappear in the montage of the ride to Aspen and reappear when they pull into town.
Continuity mistake: Harry is wearing the bullet proof vest and gets shot. Yet there's no damage to it when he opens his shirt.
Continuity mistake: When Joe Mentalino eats the rat poison pills in the cafe, he dies and the character collapses on the ground with his head facing the left. But when the body is placed on the trolly a few shots later, the "dead" Mentalino has somehow managed to move his head to the right.
Continuity mistake: Before Harry and Lloyd begin their conversation about gambling, they seem to be driving by a lake; but from the inside, they're driving by a town.
Other mistake: When Lloyd is in the bar and he has just said "Everything has to be perfect", he gives a big sigh and the camera is facing his front. Then the camera is facing the barman and he gives the same sigh. You can see from how his face changes from smiling to a frown.
Continuity mistake: At the truck stop, in the side shot in which Lloyd tells Harry to toss some salt over his right shoulder, Harry is holding his straws at an angle off the table. Then it switches to a front shot of Harry, and he is now holding his straws vertically on the table.
Continuity mistake: Right before the officer on the bike calls Lloyd a "pumpkin-pie-haircut freak", Lloyd is sitting back, straight faced, then after the officer says it Lloyd is leaning forward smiling.
Audio problem: In the very beginning Lloyd opens a bottle of beer in their apartment. When the cap falls on the floor it makes a clinking sound as if it landed on tile, however, their floor is carpeted.
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.
Other mistake: When the undercover cop (Beth) walks into the bar and orders a drink whilst sitting down next to Lloyd, the bartender gives it to her 5-10 seconds later; there wasn't enough time for him to pick out the correct glass, pour the drink from the bottle and then give it to her that quick.
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.
