Revealing mistake: On the toxic plant, where James runs from the forklift coming out of the garage door, the oil drum containing Carl flips off the forklift. When the oil drum flips, you can easily see the mechanism used for flipping it. (01:17:45)
Revealing mistake: When Louis picks up the dead body next to the garbage truck, you can see the dead body working to get a grip on the floor, making it easier to pick him up.
Revealing mistake: The shadows in the locker room aren't natural. With a few light on the ceiling and one window, you don't get as much shadows as in that scene.