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.
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)