Continuity mistake: During the crucifixion, look at Jesus' hands, there are three clear shots of this. In the first shot you plainly see his blood from his hands on the cross. In the second shot, the blood is gone from the cross. In the third shot, it's back.
Continuity mistake: When Ben-Hur is about to be transferred from his cell to Tirus after the tile struck the governor, his hands are being tied by the centurions. When he strikes the incoming centurion, his hands are free.
Continuity mistake: When Messala goes to the roof terrace after the tile incident, he checks the loose tiles. He drops one on the floor, and there are broken pieces on it that were not there before. (00:49:35)
Continuity mistake: During his brief escape Judah threatens Messala who is standing behind his desk. The arrangement of things on the desk changes many times throughout the scene, most noticeably the three books on the right. (00:53:20)
Continuity mistake: After Judah knocks out the prison guards he grabs a spear and busts into Messala's room. Two other guards standing far down the hall start running after him. Seen from inside the room, the guards enter directly after Judah. (00:52:15)
Continuity mistake: After Tirzah causes the tiles to fall from the roof, there is a wide shot from above, showing Judah and Tirzah now standing at a different part of the wall than where the tiles fell. (00:46:25)
Continuity mistake: When Jesus Christ is bearing his cross in Jerusalem, in the first shot the sign text on the cross in Latin (and presumably also Hebrew?) is displayed flipped/mirrored/backwards. In the next shot with the sign it is perfectly legible.
Continuity mistake: In the first scene of part 2 the Romans are relaxing in the bath. Then the arrival of Sheik Ilderim is announced, and when the camera switches to him the positions of many extras in the scene change, like one masseur in red (first kneeling, then squatting). (00:04:30)
Factual error: The circus maximus was built in such a way as to allow the entire track to be visible to the spectators. This is not the case in Ben Hur.
Continuity mistake: When the chariot race ends, Messala disappears from the track, only to reappear a shot later.
Continuity mistake: During the chariot race, Judah's chariot has a decorative front metal rail, and in some shots there is a plump curved cushion attached to the rail, on its inner side. It repeatedly disappears and reappears throughout the scene.
Continuity mistake: After the sheik has jumped on the chariot to take control of it, he kicks a man out and one can see the trail behind is empty. However, half a second later, many horses and riders have appeared out of nowhere and are standing right behind the sheik's chariot.
Continuity mistake: During the race, dolphin sculptures are tipped down to count the laps. Right after the third dolphin is lowered, there's a shot from below a horse and one can see that the dolphin is raised again. (02:46:55)
Revealing mistake: During the chariot race, when they're about to make a left turn around a corner, the people wave their arms. Right when they're making the turn, the arms move awkwardly fast, revealing the scene was speeded-up. (02:48:37)
Factual error: Emperor Tiberius of Rome was a reclusive and vicious tyrant by 26AD when "Ben Hur" is set. Furthermore, by that time, he had retired to Capri and was rarely in Rome. In the movie, he's the picture of Regal benevolence, basking in the love of the crowds and showering glory on Arrias in victory. In real-life that never would have happened. Tiberius' Governor Sejanus would have presided over Arrias' triumph, not Tiberius. (01:23:00 - 01:26:00)
Factual error: When Judah is being led to the galleys after Jesus give him some water you see hills in the background, and a highway is going through them. (01:05:10)