When Sharpe and Stamper have an argument over the asteroid, Truman talks about getting the radio back up. As he says this, there's a close up of the clock. Later on, you can see the countdown clock in the background but, inexplicably, there's more time on the clock. Movie magic!
The brake calipers and rims change from the wide shot of the car to the close up of the wheel. He might have been able to get away with it, but the red brake caliper in the wide shot is a dead giveaway.
When Sam (LaBeouf) goes to talk to Optimus in the cemetery, the tape that indicates where the actor should stand (i.e., the mark) is visible. The mark is green to blend in with the grass, however, it couldn't get past a few hawk-eye gazes!