Corrected entry: In the scene where Mr. Smith drops his gun in the toilet, he proceeds to clean it as though guns are not waterproof. The worst part of this scene is that the gun does fail to fire since it's apparently wet. Guns will fire when submerged in water so they will certainly fire when wet.
Corrected entry: During the robbery at the end of the film, one of the wannabe badguys extends his left middle digit towards Mr. Smith, who then shoots it off. Since the gunsel's torso was directly behind the extended finger, the bullet, unless it was deflected by the upraised phalange, should have ended its journey somewhere around his left lung.
Corrected entry: Smith picks up the baby's mother to run away from Hertz after he finds out the gun won't shoot because of the finger prints reader. On the way to the stairs, she gets a bullet in her forehead. But Hertz is shooting from behind her, so the shot should be in the back of her head.
Corrected entry: Smith is attacked by several henchmen in his warehouse apartment. He grabs the baby and jumps on the rollers of a conveyor, sliding across the room and shooting two of the bad guys in front of him while a third runs up behind the conveyor. When Smith gets to the end of the rollers he stops himself, hangs down over the end of the rollers, and shoots the man at the far end of the conveyor in the chest. If you work out the math on the angle he is firing from and the length of the conveyor, it is an impossible shot. The man would have to be at least 27 feet behind the conveyor for the bullet to clear the rollers and hit him in the chest; in reality he was standing much closer.
Corrected entry: In the very beginning we see Mr. Smith eating a carrot. He bites the pointed end and eats it. Later he kills the bad guy by sticking the carrot in his mouth and punching it through the back of his head. The carrot, as it's sticking out the bad guy's head, now has no signs of being bitten at all and has its original point on it.