Revealing mistakes: As Robert Neville checks the right eye of the bedridden boy, the boy's dislodged contact lens slides back into place.
Revealing mistakes: In the stadium, one of the Family members moves to cover his eyes before the flash bomb goes off.
Revealing mistakes: When Neville injects himself in the leg with the experimental vaccine following the helicopter crash, a "blood pouch" is clearly visible in his pant leg.
Audio/visual unsynchronized: The 8-track that Robert Neville puts into his car stereo at the beginning of the movie can very briefly be made out to be Frank Sinatra's "Strangers in the Night". What actually plays on the soundtrack is Max Steiner's "Theme from 'A Summer Place'".
Revealing mistakes: When Robert Neville is in the helicopter which is supposedly spinning out of control, the reflection of the same tree can be seen in the copter's windscreen throughout the entire flight.
Audio/visual unsynchronized: After Neville puts out the fire on the front of his car in the garage you can hear a short burst of "fire extinguisher" sound when his hand is not squeezing the extinguisher handle.
Plot holes: In a city supposedly laid waste, Neville has to resort to running a generator any time he requires electricity. He does so to power his apartment; he does so to power up the projector inside the cinema when he goes to watch the film. But this city with no surviving infrastructure (in the opening scenes, as he's driving around in the red convertible), all the traffic lights are powered up.
Revealing mistakes: In the opening scenes when Neville is driving through the supposedly empty city, another vehicle can clearly be seen driving along the same road in the distance
Revealing mistakes: As Neville drives through the deserted city in the opening scenes past the "Tishman" building a person can clearly be scene walking back up the footpath on the right hand side
Continuity: In the opening scenes when Neville stops to shoot at a hooded figure inside a building, his red jerry can is clearly visible before he shoots, in the back seat. After shooting he drives away, and the jerry can has disappeared. A minute later when he crashes his car, the jerry can has reappeared, but it has turned around and is lying against the back of the rear seat.
Revealing mistakes: As Neville drives through the deserted city in the opening scenes numerous people can be seen walking along the footpaths and crossing the roads
Crew or equipment visible: The camera crew is reflected in the black stone pillars when he is jogging along the Dorothy Chandler Pavilion.
Crew or equipment visible: During the inquisition you can see reflections of the crew in the silvered glasses of the "family".
Revealing mistakes: When Robert Neville is shooting at The Family (who is behind a car), you can clearly see a fairly straight line of bullet holes running horizontal across the car. As this happens the tires pop even though it would appear the bullets never hit near them. The scene cuts away from the car. When it cuts back to the car, the bullet holes are gone.
Miscellaneous: In the beginning of the movie, when the camera pans way out to show Robert Neville walking down the street, you can see a car driving down the highway from left to right in the far left part of the screen near the tall building in the background also on the left in the horizon.
Audio/visual unsynchronized: When the family is shooting the flaming ammo via catapult up to Robert Neville's residence there is a sound effect heard with the projected object which sounds like a flaming type noise. The last one however, while Robert is about to take aim with his gun, is thrown without being on fire, but has the sound effect to go along with it anyway.
Miscellaneous: When Robert Neville is checking out Richie for the first time, you see Robert rub Richie's face under his left eye which also removes his white make-up.
Revealing mistakes: When Neville and Lisa ride on the motorcycle it is obvious that it is not Charlton Heston driving, but apparently a stunt double.
Revealing mistakes: As Neville zooms past the Family members on his motorcycle, no light appears on their bodies in the POV shots despite the fact the motorcycle light is on.
Anachronisms: In one of the early flashback news sequences, the reporter warning people to stay in their homes concludes with 'CONELRAD channel' - CONELRAD was an acronym for Conrtol of Electromagnetic Radiation developed by the FCC during the Cold War, and was abandoned in August of 1963, replaced by the Emergency Broadcast System in the same month. Any 1970s alert would have used the EBS, not CONELRAD.