Eminem reportedly turned down an offer to star in the lead role. But an MTV report quoted director Doug Liman saying that his plan to have Eminem in the movie was dropped right after he met Hayden Christensen.
The crew was allowed to film inside the Colosseum for three days, under 3 conditions: no equipment could be placed on the ground, they could only shoot from 6:30 to 8:30 am and 3:30 to 5:30 pm to avoid disturbing tourists, and the only lighting allowed was natural sunlight.
In the original novel, Roland Cox's first name was Brian. It was most likely changed to avoid confusion with actor Brian Cox. The character's name was changed from Brian to Roland to reflect the stories of ancient France. The paladins, led by Roland, served Charlemagne similar to the stories of England's Arthur and the knights of the round table. Since the paladins were not in the novel on which the movie was based, and were added to the screenplay, the name Roland is more appropriate.
Roland (Samuel L. Jackson) encounters David (Hayden Christensen) and attacks him with a saber-like electric prod. This can be considered an inside joke among fans of the Star Wars series. Both Jackson and Christensen famously starred in the prequel trilogy as Jedis.