Several people that played Texan extras in the movie are actual descendants of the defenders of the Alamo.
In his autobiography "The Billy Bob Tapes", Billy Bob Thornton said that if he could go back to any time in his life and relive it, he listed this film, Bad Santa (2003) and when he worked for the Arkansas Highway Department in 1979.
An extra had grabbed a bag of Doritos from Craft Services before being called to the set. He stuffed it into his costume and got into formation. When action was called, the group charged across the field. When he was "shot" and fell dead to the ground, his bag of Doritos popped out. The scene had to be re-shot and from then on everyone had to be checked frequently.