Continuity mistake: When Lisa sees the family marching towards Neville's house, in front of the building on the left is a waste can and a mail box on the opposite corner. When Neville drives by the same building a short time later, there is now a dark car parked in front, two other cars parked on the sidewalk further down the street, and the mail box has moved across the street by the door.
Continuity mistake: Robert Neville ends his morning run in a downtown Los Angeles left empty by biological warfare except for vampiric mutants led by Jonathan Matthias. Only trouble is, when director Boris Sagal purports to show the audience how "dead" Los Angeles is by displaying four wide shots of the city after Neville yells "Hey, Matthias." you can see a white car in the right background of the last L.A. wide shot moving along quite briskly.
Continuity mistake: In the opening scene when Neville almost hits the armored car, he crashes his car into the curb. The shot shows the car from a side view hitting the curb, and the tire going up over the curb, still intact. Next shot shows Neville getting out to check the damage, and the tire is now flat.
Continuity mistake: Near the beginning, Neville sees the sun just above the horizon, about to set, and he flees for his shelter, racing through city streets. As the camera repeatedly cuts to follow him, it's obvious that the sun is still high in the sky, nowhere near sunset. In fact, the sun's position is constantly changing from one shot to the next all throughout this film.