Revealing mistake: Very poor diopter work on the Las Vegas stage: the audience is "split in half", one part very blurry behind DeVito's head, and the other half crisp and clear.
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: 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: Strangulation scene that uses a rope, the rope never goes around his neck. (01:53:00)
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: Whenever Ralph is driving Travers in the limousine and the exterior of the car is seen in a long shot, there is no one riding in it other than the driver. From every view point of the windows that can be seen, there is no passenger inside where Travers is supposed to be seated.
Revealing mistake: After exercising, Valerie is in bed watching the news, then the scene changes to a shot of her house showing a Honda Accord at the 2002 meeting but this model did not get released until 2008.
Revealing mistake: In the opening scene right after she's put in the truck, she is lying on the bed looking in a mirror above her and her earrings are hanging parallel to the ground as though she was standing. (00:02:12)
Revealing mistake: There's something odd about the chair that is (or is not?) to the right of Monsignor Kelly when Stu goes into his office to talk. Only part of the back of the chair can be seen and it is not directly in front of the Monsignor, but there is not enough room for the seat part to be there (otherwise, the Monsignor could not be standing where he is). Without any indication that the Monsignor or chair moved, the Monsignor is later able to rest his right hand on the chair's back. (01:13:57 - 01:14:37)
Revealing mistake: Callahan proudly shows to a policeman an issue of the Portland State University "Vanguard", the magazine that is publishing his comic. Looking at the prop, it is instantly suspicious because Callahan's name is all over it like he's a celebrity, and in fact, the article on it is nothing but a copy and paste of Timothy Egan's "Defiantly incorrect" article from The New Yorker celebrating John Callahan's talents in 1992. (01:12:55)