Continuity mistake: When Leonidas, and presumably all the other Spartans, use their spears to clear their shields of arrows after the arrow shower from Persian archers, the tips of the arrows are still visibly left on all their shields. In the next shot, when the Spartans regroup for the Persian cavalry charge, the arrow tips are gone. (Granted, this is a highly stylized movie based on a comic book, but that does not change the fact that this is a continuity error.)
Continuity mistake: Saigo is told to empty out the chamberpot because it is full. But it is not full when he is taking it outside to empty it.
Continuity mistake: Many of the flying scenes have unrealistic changes of altitude. The planes will be able to see people on the ground, and in the next action shot, they will be thousands of feet in the air.
Continuity mistake: After they ditch Burns in the woods, they plan to go through a small graveyard. As the captain starts briefing the squad we see him taking the cigar out of his mouth. When it cuts the cigar is back in his mouth. (00:21:40)
Continuity mistake: When the "Flag-Raisers" begin stripping down to go swimming, they show a few of the Marines already down to their boxers. They switch to a shot of Bradley and then back to the Marines and all have their pants on.
Continuity mistake: When Teddy has delivered Damien's letter to Sinead, he puts his cap on, gets on his motorcycle and puts his pair of goggles on the handlebar. The scene then cuts to a wide angle and the goggles are around his neck.
Continuity mistake: After Pierce Brosnan does the deal for the bullet, Anjelica Huston rides off with his horse attached to her carriage. Only problem is we see the entire exchange, and at no point does anyone tie the horse on.
Continuity mistake: When Jack shoots the cop Urick, the slug perforates his suit coat, both front and back, as well as his right lung. However, when he rendezvous with the Russians atop the parking garage, his suit coat is pristine. Had he changed into another identical coat, would he have not changed his bloody shirt and tie at the same time?
Continuity mistake: When Victoria Wood is walking down her old street, the shot is flipped. Her coat is fastened left to right and her hat band is facing the wrong way.