Revealing mistake: When the Penguin is sliding down the zip line, just before he hits Batman you can see Batman throwing a punch at nobody, he is swinging at empty air.
Revealing mistake: Near the end of the film when a building is collapsing and people are running to escape the falling debris, several women along with James Coburn are running up some stairs; a block of cement falls and hits actress Gina Golan right in the head. Instead of killing her on the spot, the bolder merely bounces off her head and she continues running up the stairs. (01:40:55)
Revealing mistake: During Cole and Mississippi's night patrol, a bunch of horsemen start making a fuss in the street. When Mississippi dives under their horses, there is an interruption between when he dives, and when he (supposedly) lies in the horses' path. Evidently, this scene was made by joining two cuts.
Revealing mistake: When Blondie is to be hanged by Tuco, and saved by an extremely lucky hit by a Union mortar, you can see that the wall that will be hit by the grenade has been blown to pieces at least once before; the bricks have no mortar between them, and there is a large circular scorched area on the brick wall. (00:47:10)
Revealing mistake: In the scene where Lt Stachel and an ordinary soldier search for the wreckage of Stachel's unconfirmed first shoot-down, it is supposed to be dark and pouring rain but blue sky is seen in the background.
Revealing mistake: When Sir Rodney leaps from the banister onto the chandelier during the fight at Chateau Neuf, it is not Sid James but a stunt double.
Revealing mistake: At the end of the car chase when the two cars collide, the cliff shown to the right is a painting added to the scene to suggest a sharp drop off.
Revealing mistake: In this scene we see Frank Sinatra in a diving suit and helmet being lowered into the sea to look for a sunken submarine. As he is being lowered you can see the sun's reflection on the walls of a tank, meaning it was filmed in a large tank of water.