Revealing mistake: The Aspen lift operators are wearing Copper Mountain uniforms. Copper Mountain is in Colorado, but it is over two hours away from Aspen.
Revealing mistake: When the air bag inflates at the airport and Lloyd is wrestling with it for a split second he pulls it back and you can see it is not attached to the steering wheel. (00:08:40)
Revealing mistake: When Harry is lying on the bed at the end - you can see he's not wearing a bullet proof vest as the extra bulk they cause is not visible on his torso. However once he's shot, the bulk is visible under his shirt for the remainder of the scene.
Revealing mistake: When Lloyd and Mary are going to the airport, you can see a white van out the rear window. The driver is turning the steering wheel, but he keeps going straight. (00:04:30)
Revealing mistake: The Asian man at the airport terminal is struggling very hard not to laugh at Jim Carrey's antics, as seen from his reflection in the glass.
Revealing mistake: When Jim Carrey and Jeff Daniels are fighting at the park over the briefcase, the snow is obviously foam or some other material. The same thing also happens right when they get to Aspen and walking from the street on to the curb, the snow moves. (00:59:24)
Revealing mistake: When Harry is talking to the lady at the gas station, and his legs catch fire, you can see the burn gel on his pants.
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.
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.
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.
Revealing mistake: Prior to the animal show, just before Harry feeds the second dog, you can see someone in the back throw a treat through the curtains to get the dog to go up front. (00:02:50)
Revealing mistake: During the tongue scene, when Mary is pulling Harry's tongue off the ski lift, you can see Harry's real tongue right under the fake stretchy one. (01:16:50)
Suggested correction: If you look really carefully you will see that this is a part of his lower lip folded a little bit.
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)
Revealing mistake: When Lloyd drives into the back of a car at the airport his air bag inflates and it looks it is made out of thin rubber translucent material. That is not what real air bags are made of. (00:08:40)