Revealing mistake: When it starts hailing inside the cabin, you can obviously tell that the night sky has wrinkles in it, revealing that this "sky" is a black curtain in a stage.
Continuity mistake: When Drake sneaks up on Steve while he is urinating on the tree, he turns Steve around, and as happens in many films when someone is interrupted while urinating, his genitals are magically back in his pants. You can then hear Steve urinate on the ground a couple times as Drake continues to intimidate him, which wouldn't be possible if his genitals were back in his pants.
Revealing mistake: Could the scene when the big rock knocks down the cabin be any faker? You can easily tell that the cabin and the rock are miniature models.
Continuity mistake: When Mike is talking about seeing his brother while Steve is asleep, you see the Playpen magazine sticking out from under his pillow, on top of a 2nd magazine. When Mike approaches him, the Playboy magazine is under the covers next to Steve and there's only one magazine under the pillow.
Other mistake: When we see the front page picture of Mike with the alcohol and joint, he's pouring the alcohol over his bottom lip and chin, going down the front of his shirt. This doesn't match what we see him do. It does appear that Mike spilt alcohol on himself when off camera, but the wet spot is on the right side of his jacket, but not down the front.
Audio problem: The last scene begins with Al and Mike walking towards the plane speaking. Al asks "are you sure you don't want a job on my staff?" Mike then responds by stating; "you know what Al... I don't really think I'm cut out for politics." Al then is heard laughing at this. It is very clear the audio laugh is actually that of actor David Spade and appears to be placed over a most likely silent smile of Al. (01:20:00)