Factual error: A key plot point hinges on the Iraqi fellow believing he has shot someone but caused no harm. A brief shot of the bullets he has loaded his revolver with reveals that they are black powder blanks. Such blanks produce large clouds of white smoke when fired (indeed, they are used specifically to produce that effect in movies), but the shooting scene shows no smoke at all.
Revealing mistake: When Daniel (the locksmith) goes home, the lamp next to his daughter's bed is on. After he finally tucks her in, he puts his finger on the light switch on the wall, but it is already in the "off" position. He doesn't flip the switch in either direction, but you hear an audible click, and the lights go out as if the lamp was controlled by the switch.
Audio problem: When the two friends run over the Chinaman and they discuss over it, you can hear them, but not see them, say, "Man this is so f***ed up" "No s**t". The background sound is clean as opposed to the live one, and the voices sound totally different to that of the actors. Furthermore, in a brief shot of the guy in a yellow jacket is seen, and he is not mouthing the words.