Continuity mistake: One of the first shots in the picture is a wide angle establishing shot showing a street scene in Jerusalem, with milling people, animals, etc. A tall figure in the background is slowly walking toward the camera. The figure is Charlton Heston, and the shot is an earlier segment of a shot used later in the movie when Ben-Hur is returning home from a trade expedition. Heston's costume is the same, but he's only clearly recognizable in the second sequence. Since the two scenes are set 33 years apart, perhaps the earlier figure is Ben-Hur's father.
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.
Continuity mistake: During Ben Hur and Messala's duel on the chariots, Messala's wheel-scythes tear away most of the right hand side of Ben Hur's chariot. When Messala has been thrown and Ben Hur crosses the finish line a few moments later, however, the camera has zoomed out far enough to reveal that his chariot is perfectly intact.
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.
Continuity mistake: Right before the chariot race, Sheik Ilderim is on Judah's left side, pointing out the spikes on Messala's wheels. There's a shot of the wheels and then back to Judah, where the Sheik is now on Judah's right side. Judah holds the Sheik's forearm as the fanfare starts. Then a long shot, showing the Sheik, now on Judah's left side again, and Judah removing his hand from the Sheik's forearm.
Continuity mistake: At the end of the chariot race, a heavily bloodsoaked Messala is taken to receive medical treatment. While something is done to his legs out of shot (amputation, presumably) an orderly in a clean white tunic leans his whole body weight on Messala to hold him down on the bed as he writhes in agony. When the orderly stands up, we see that his tunic is still spotlessly white.
Continuity mistake: In the parade of chariots before the race, the riders are shown circling the track once before making their way to the starting line. As they emerge from the stables, the horses and chariots leave very noticeable tracks on the ground so you can trace their progress around the track. The riders head down the right side of the track (from the perspective of the stables) then make the wide turn to head down the backstretch, and then make the wide turn back onto the right side of the track where they started. The film then cuts to a wide shot of the riders heading back down the right side of the track for the second time, but the track ahead of them and all the way down the backstretch is now clean of any tracks. It's clear this shot comes from when the riders first emerged from the stables. The riders then stop on the starting line on the backstretch, which means they were either transported to the other side of the track without making a third turn, or they did 1 lap around the track in the space of 1 and a half laps.