Character mistake: In a conference with Crockett and Bowie, Travis states that Fannin in Goliad is preparing to relieve the Alamo and will be ready to "march south by the end of the week." Goliad is 90 miles south of San Antonio. To relieve the Alamo, Fannin would need to march north.
Character mistake: At the very end of the movie, Jack Lemmon begins dealing cards for the gin rummy, but he deals about 14 cards before the fade to black, in a 10 cards game. (01:59:45)