Factual error: When Robert Neville is driving golf balls off the deck of the ship, he sees a deer on the mainland. He and his dog go in pursuit. In a wide, distant shot, we see the deer fleeing full-tilt down a city street, with Robert Neville pursuing at the same speed as the deer, only about 10 yards behind the animal. Impossible. A panicked deer can run over twice as fast as the fastest human being.
Other mistake: How did Anna drive from Maryland to New York, where Dr. Neville was, if all the bridges were blown out?
Answer: I thought people jumped on another helicopter causing it to spin out of control, and that one crashed into their helicopter.