Character mistake: The shady gun dealer is showing off his merchandise. He picks up a handgun, and he says "it's your standard Beretta 9mm I'm sure your familiar with it..." as he's manipulating it, but he's really holding a CZ 75, a Czechoslovakian made firearm. The make and manufacture is always stamped on every gun produced. (00:40:30 - 00:41:30)
Visible crew/equipment: When Major Carver gets in his car to chase after "David", the entire camera crew is reflected in the side of the car when it's reversing.
Answer: The officer knew that David would methodically clean after himself.