Revealing mistake: During the chariot race, where the contestants are riding towards the screen, tyre tracks from the camera vehicle are clearly visible imprinted in the sand.
Continuity mistake: Ben-Hur places his crown on a table when he visits the fallen Messala, but upon returning the table and crown are gone.
Revealing mistake: When one of the ships collides with the other, you can clearly see that the rowers being hit are dummies.
Continuity mistake: When Judah takes rest on his way to Jerusalem funny things happen with his headgear. First, when he lies down it suddenly disappears under his head. Then he falls asleep, and when Balthasar from Alexandria approaches him a little later and he quickly gets up there is nothing under his head and back.
Factual error: Al-Tair and al-Deberan are the names of the Arab Sheikh's horses, and he states they're named after the stars. Those stars were given their names by Arabian astronomers, and calculated astronomy by the Arabs emerged during medieval Islam in the 7th and 8th century CE, 674 years after the plot of the movie takes place.
Continuity mistake: Ben Hur's horses change position. When the chariots are preparing for the race and at the starting line, the horse with the pink nose is third from the left, but at the end of the race, the pink-nosed horse is fourth from the right.
Continuity mistake: At the very end, the scaffold that was used to erect the crosses vanishes between shots.
Revealing mistake: When Stephen Boyd is showing off the spikes on his chariot wheel you can see welding beads along the projecting hub.
Deliberate mistake: During the chariot race, the chariots crash together but the arrangement of the horses make it impossible for them to actually collide. In some instances (particularly in an aerial shot as Ben Hur and Messala round the turn) it is obvious that they repositioned the shaft of the chariot to between the first and third horses instead of being in the centre between the second and third.
Factual error: When Messala is passing through Nazareth, he says they will be in Jerusalem by tomorrow night. Nazareth is approximately 90 miles from Jerusalem. It would take three days to cover that distance, not one.
Continuity mistake: When the baskets are being loaded to be lowered into the Valley of the Lepers, someone loads two heads of lettuce onto a basket. Just as the basket is being lowered, someone else throws in three more heads. When the basket hits the bottom, there are only three heads of lettuce.