Continuity mistake: When Sandy and Sal are in the tent looking at all the papers in the ammo crate look at the guy smoking a cigar. It goes from 2 inches to a brand new one in at least 10-15 seconds.
Suggested correction: It doesn't take very long to put a new cigar in your mouth.
Revealing mistake: When Charlie Sheen fires at the villagers' feet there are no shell casings being ejected from the weapon, and there is also no muzzle flash.
Suggested correction: During the day time, the only time you'll see a muzzle flash is if the weapon is aimed straight at you. Hollywood exaggerates muzzle flash for artistic purposes.