Three of the actors were considerably older than the real-life people they played: James Arness, 64, played Jim Bowie, who was 40 at the time; Brian Keith, 66, played Davy Crockett, who was 49 at the Alamo; and Lorne Greene, 72, played Sam Houston, who was 43.
Of the Alamo's roughly 180 defenders, only 13 were native-born Texans--and 11 of those were Mexican--and 50 were European-born.
No one is quite sure from what illness Jim Bowie was suffering. At the time it was diagnosed as typhoid pneumonia, but was likely tuberculosis.