Character mistake: When LT. Col. Robert Neville's wife fails the eye scan and he's ordering the soldiers to scan her again, the soldier that escorts them to the scan point, and later to the helicopter mistakenly uses Will Smith's real last name. You can faintly here him identifying LT. Col. Robert Neville to another soldier as LT. Col. Robert Smith.
Character mistake: As Lex is studying the recording of when Superman's body vanishes, he says "A 19 second black out at 3:47 AM." But the clock on the video shows it goes from 3:47:05 when the blackout starts, to 3:47:26. The blackout was 21 seconds, not 19. (00:45:55)
Character mistake: Alice shoots the henchmen, the black officer is attempting pull a gun from his shoe but in closeup his leg is white, then back. (01:06:25)
Character mistake: Sam says that Archibald Witwicky explored the Arctic Circle in 1897. But when Frenzy finds the article, it is dated 1895.