(at around 20 mins) Llewellyn's glasses disappear from his face between shots. He's wearing them when he asks Groat, "10 o'clock, right?" and they're suddenly gone when Groat immediately responds, "Sure."
The green Mercury the hit man is driving in Act 1 to rig the ignition activated shotgun device has license plates (849 ASB) that are clearly not genuine California plates. The lettering style differs and there appears to be no embossed texture.
The pipe bomb is so clearly visible underneath the steering wheel, the victim would have noticed it right away. It should have been hidden better to be more realistic.
Just before the car bomb at the very beginning, two people behind the car are clearly watching the filming. They may have been extras who entered the scene too early. Seconds later, a crowd of onlookers gather in the area.
Lots of people watching the filming throughout the airport scene. This begins as the cars first pull up -- people can be seen looking out the windows at the cars and actors.
At the beginning, the explosive device with the shotgun round taped to the steering wheel is so obvious, not even hidden that it would have been noticed immediately by the victim.
Styles' rap sheet describes him as having brown eyes, but they are very obviously blue.
When we see Stone and Keller inside the car from the back seat perspective, the rear view mirror on the windshield has clearly been removed. When the scene switches to the outside of the car, there is a rear view mirror on the inside of the windshield.
When looking through the back window of Mary Rae's Ford Maverick on the way to the airport a camera mount can be seen.