Lucas tries to open the door to the bank to catch the robbers in the act. The camera from inside of the bank shows the door knob, then pans upward to show that the door has been bolted. Lucas then fires his rifle where the door knob is, and the door springs open. He should have been shooting higher, since it was the slide-bolt that was preventing the door from opening.
When Lucas looks through the bank's window while the surveyors are inside, he sees one through the mirror on the wall. The surveyor is clearly visible, given the amount of light shining on him. But when they show a closeup of the him, he's suddenly in shadow despite not having moved.
When one of the surveyors opens the door to the safe it swings open easily as if it is very light weight. Too, there are no bolts around the door, showing it to be a prop and not a real safe.