Factual error: In one scene, Neville is sitting alone in a theater watching "Woodstock". He has obviously done so many times since he has memorized the dialogue. The projector, however, appears to be running itself. Theaters at that time used dual projectors and it was necessary to change reels approximately every 15 minutes, but there is no sign that Neville does so. One might also wonder why Neville would deliberately choose to sit alone in a darkened room where the "tertiary cases" could easily trap him.
Factual error: In the opening scenes of a city deserted for several years, lots of smog can be seen at the base of the mountains in the distance. Smog is entirely man made and would disappear completely in a matter of days once all human activity stopped.