Revealing mistake: When Mark Wahlberg removes the shrapnel from his leg, it is pretty obvious that it is a fake leg. If you look at and compare its dimensions to the rest of his body, you can see that that would be the leg of a giant man. The thigh is way too long, and the whole leg is way too big for his body. You can also tell by his body posture that his real leg goes into the couch he is sitting on.
Revealing mistake: Back at his NAACP homebase, Marshall meets with the boss who is already sending him to deal with another case. In the close-up of the newspaper he's reading, check out between the actor's fingers. You can tell that half of the article, which begins in English, suddenly switches into Latin 'lorem ipsum' filler text. (00:06:20)
Revealing mistake: Why does the railroad station look so old? It should be almost new at the time of the film.
Revealing mistake: When Vercingétorix leaves the Romans to go to Gergovia there is a stone mason by the road carving what is probably a distance marker. The man's chisel is obviously not in contact with the stone - while he is banging it with the hammer it is waving around in the air. (00:17:00)
Revealing mistake: When Caesar's ship arrives in the Alexandria marketplace, he tells his men to "go marketing" rather than force their way through the crowd with swords. Rufio says "you're not serious?" He then silently mouths along with Caesar's reply, "We shall shop our way to the palace steps." (00:11:30)
Revealing mistake: Near the beginning, after the corporal has burned his finger and tells the other corporal that Lawrence is balmy, O'Toole begins to run up the stairs to meet with a general. After O'Toole is out of view of the camera, you can tell he has stopped running up the stairs by his shadow on the wall not moving, because he knows that the director is about to shout "cut".
Revealing mistake: In the Atlanta party scene, we are supposed to believe it starts with a single long take. However there is a sneaky edit when Frank crosses the threshold of the room. He emerges at a slighty quicker pace and his hair is suddenly messed up. (01:10:35)
Suggested correction: There is nothing obvious in this scene that supports this. When he emerges on the other side, he bumps into his friend so suddenly that you can't tell if he was walking at a different pace. The reason his hair is messed up is because he bumps into his friend. He then yells at his friend, jerking his head around as he does so, which messes up his hair even further, which can be seen.
Even if it were true, it wouldn't qualify as a mistake. The shot may be intended to appear as a single shot, but that doesn't mean it's a mistake if it isn't.
Revealing mistake: At the very end, a violent storm engulfs Jerusalem and the people viewing the crucifixion. In the close ups, you can see rain falling, but no one appears to be getting wet.
Revealing mistake: After Chris and his son learn that there are no more rooms in the shelter, the crowd begins to disperse. One homeless man touches a parking meter which moves easily, like a lightweight prop. (01:40:55)
Revealing mistake: Strangulation scene that uses a rope, the rope never goes around his neck. (01:53:00)
Revealing mistake: When Ali is in the rain on the pay phone at the motel it is a modern phone, not from the era they were trying to portray.
Revealing mistake: In most of the scenes of the film, the famous filly is impersonated by a colt.
Revealing mistake: The paddle steamer on which Wilde crosses the Channel has her name "Waverley" visible on the bow. The Waverley, the world's last seagoing paddle steamer, was launched in 1946, 46 years after Wilde's death. Replacing the name with the name of a real paddle steamer of the era would probably have been a good idea.
Revealing mistake: When Mark gets a nasty note from a Harvard classmate and storms out of a computer class, a directory sign saying "USC College of Letters, Arts & Sciences" (ie. University of Southern California, not Harvard) can easily be seen on the hallway wall through the door as he opens it and walks out.
Revealing mistake: When Majestic is discussing killing the police to Marcus, the shot of the Uptown station house has the same figure ascending its steps in both shots, revealing that one shot was used twice instead of actually using two separate shots of the same location.
Revealing mistake: When Tom Cruise and Bill Nighy go to see Tom Wilkinson for the first time there are 2 reverse shots from behind Tom and Bill - if you look you can see Tom's hand is still there - it has been digitally removed in all other shots.
Revealing mistake: In the opening scene the Club's dancers are in full-swing, including the tall, lanky gentleman from Lautrec's famous Moulin Rouge poster, the one with the very angular, extended nose and chin. In several closeups it's very plain that the chin is a makeup appliance: the edge of the appliance isn't blended very well with the actor's real skin.
Revealing mistake: Watch carefully during the fight scene between Billy and Rifki, you can see the stuntmen a few times.
Revealing mistake: When Paul Castellano is shot, there is a blood spurt shown from where the bullet hits, but the position of the gunman who fires at him doesn't match the direction the blood spurts. The gunman is across the street facing Castellano at an angle, but the blood spurt shown could only be achieved if the two were facing each other directly. (00:56:10)
Revealing mistake: After Frank shoots Kevin and Kevin's SUV hits the curb, the background/scenery changes as well as the position of Frank's car. Frank initially pulls along the curb (behind the SUV) with his car at about a 30° angle. The next time Frank's car is shown, it is almost perpendicular to the curb and the Food Mart. When Rupple and Frank have their guns aimed, they would be aiming inside the Mart, not toward Kevin. Objects in the background also change (e.g, fire hydrant, telephone pole appear). (00:16:48)