Continuity: When Winston and Julia are together in the room upstairs for the second time, Julia asks Winston what time the clock says. He responds that it is 21 hours, or 9pm. When Julia leaves and Winston picks up the glass ball off the table, the clock behind it says 2:30.
Continuity: After the rack torture scene, O'Brien removes Winston's front tooth. Later, in the rat mask torture scene, his tooth is back again. (However, in the book, Winston given dentures after O'Brien pulled the tooth, but this was not explained in the movie.)
Revealing mistakes: When O'Brien's assistant is releasing Winston in the torture chamber, O'Brien tells Winston to "get up," just before the assistant disabled the final restraint. The restraints make a distinctive sound when disabled; however, it is clear that his last restraint is not released, yet he stands up anyway.