Warner Bros. refused to do a director's commentary for the DVD release, so Darren Aronofsky recorded one in his living room and released it on his website.
Instead of using CGI, Darren Aronofsky chose to do the visual effects for the film by using micro-photography of chemical reactions on tiny petri dishes. He has said that CGI would take away from the timelessness of the film, and that he wants the film to stand the test of time.
Of the seventy extras cast as Mayan warriors, twenty were actual Mayans flown in from Guatemala. Fernando Hernandez, who played the Lord of Xibalba, was the only one who could speak English. Before shooting at the Mayan pyramid, the Mayan actors blessed the set.
Darren Aronofsky originally planned a major battle between the Mayans and the Conquistadors, but budget cuts and the release of grand epic battle films (Peter Jackson's "Lord of the Ring" films, Troy (2004) and King Arthur (2004)) made him change his mind and rewrite be mainly between Tomás Verde and the Mayans. Aronofsky realized that this worked out better: one man against the army represented a man defying odds.
In early 2002, Darren Aronofsky cast Brad Pitt and Cate Blanchett in the central leads of Tom and Izzi with a budget of $75 million. During pre-production, Pitt and Aronofsky were having major creative differences, so Pitt left to film Troy (2004) instead, and the film was shut down, and the sets and props built in Australia were auctioned off. In early 2004, with a smaller budget of $35 million, Aronofsky cast Hugh Jackman as Tom and Rachel Weisz replaced Blanchett as Izzi. Warner Bros., who had invested $20 million in the canceled version, agreed to finance the new, cheaper version.