Visible crew/equipment: Very early on in the movie, Neville is happily driving around the deserted streets. Half way through this scene the camera shows us Neville's view out the front windscreen of the car. Ahead, moving cars can be seen crossing the intersection, obviously where the streets hadn't been blocked off for the filming of the movie.
Revealing mistake: When Neville gets back to his fortress-apartment, he boots up the video surveillance system, switching on several closed-circuit monitors. The very largest screen, however, shows himself, looking toward the screen. As he turns about his image on the screen doesn't turn the correct way; it moves like a mirrored image: he turns to the right, the image turns to the left. The image ought to turn in the same direction. The image in the video screen was photographed separately (and not quite inaccurately), and added later in post-production.