Other mistake: When Balian talks to God on the hill where Jesus died, after he says his line, the next shot is him sitting down overlooking the empty valley below. A white light travels from right to left going 45-50 mph. Nothing back then could go that fast, and even if anything could, a torch is yellow and red, and even if it could be white, no rider can ride that fast with a white-light torch and keep it from going out - leaving us to assume it's a car.
Other mistake: The exact same background shot of a Ventura bomber followed by two single-engine planes flying left to right is used three times during the film, twice at the beginning as they are planning the mission on the beach and then once at the end when the raid is over.