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.
Revealing mistake: Watch when Dutch throws the flash grenades during the stadium scene. When seen igniting on the ground, they are positioned closely behind large boxes and other bulky debris, to hide the special effects used to create the light. It would be virtually impossible to toss the grenades any distance and then have them drop down into place so perfectly on the far side of the conveniently placed obstacles.
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.
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: When Neville crashes the jeep you can see the explosives being thrown under the car. The camera angle changes and you see Neville taking out the explosives from his backpack and throwing them again.
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.
Audio problem: Neville attempts to fire at Matthias with his submachine gun, but it jams. His lips don't move when you hear him say, "Jammed!"
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.
Revealing mistake: In a wide shot of the supposedly deserted city, car and bus traffic can be seen in the middle background at the left of the frame, driving along the roadway. (00:27:25)
Audio problem: Lisa is nude and gets up to close the windows. Neville comes out of Richie's room and turns to see the naked Lisa sitting.on the bed. You can hear her speak, but her mouth never moves.
