Character mistake: At the beginning of the movie, the German sub gets surprised and severely damaged by a destroyer. The sonar man first notices the enemy destroyer approaching, but only a short time before the destroyer is already literally on top of the sub. German sonar at the time had the capacity to detect ships up to more than 7 miles away, so the sonar man really had to be asleep at his sonar station not to notice the destroyer approaching. (00:03:40)
Character mistake: When Maximus is talking to Marcus Aerelius, he mentions that his wife has black hair. But in the scenes where we see her, she actually has brown hair. (00:24:40)