Other mistake: When John Wayne is running about near the chapel with a torch. You can see inside the chapel a lot of Mexican soldiers just stood there not doing anything.
Factual error: Approximately 2 hours and 10 minutes into the "restored" full-length video version, there's a birthday party for little Lisa Dickinson, and the Alamo defenders sing "Happy Birthday" to her. The Alamo battle happened in 1836. According to David Ewen's "All the Years of American Popular Music," the song "Happy Birthday to You" was composed and copyrighted by sisters Patty and Mildred J. Hill, first as "Good Morning to All," in 1893.
Other mistake: When Bowie and his men first enter the Alamo, Travis calls for the colors ceremony and the detail marches to the flagpole. One section is ordered to "halt", then the order "about face" is given. However, the detail does a "right face" instead.
Revealing mistake: When Crockett, Bowie and their men are about to destroy the giant cannon, several of the men are standing right next to it at the moment one of them tosses the torch on the touch hole. Then, there's a big flash at the touchhole. In the very next shot, right before the cannon explodes, we see the cannon, but everyone has disappeared. There was no time for them to flee completely out of sight.
Continuity mistake: In an early scene Travis and Dickenson are in Travis's office. Travis goes to the mantel, gets a cigar and pours himself a glass of sherry. In a later scene, when Travis meets Crockett in the cantina he refuses a drink from Crockett claiming he doesn't drink, ever.
Other mistake: In the fight scene between Emil Sand, his henchmen and Davy Crockett in the street, it is very clear that it is not John Wayne fighting, but his double. Maybe Wayne could not fight, direct and produce at the same time?
Factual error: When Bowie first walks into the chapel, you can see all the way back to the eastern wall. By this time, there would have been a dirt ramp leading up to two 12-pound cannon that overlooked the wall. In the same scene, the doorway to Bowie's left is where the powder magazine would have been, and to the right is where the women and children were. In the movie, these uses for the rooms are reversed.
Factual error: The mock-up of San Antonio de Bexar shows the buildings connected mostly along a single street, like towns in innumerable westerns. Actually, San Antonio was laid out with its buildings around plazas, in the Spanish style.
Factual error: The movie's opening scene manages to get wrong almost every historical detail except the names. Sam Houston was never in San Antonio with Colonels Neill, Travis, and Bowie. Then-governor Henry Smith - not General Houston - made Travis a colonel (in December). Bowie did a lot of drinking and carousing, but that never caused him to be demoted or to lose a command. Bowie did marry into the Mexican aristocracy, and he acquired a lot of land, but it would have been ridiculous for Travis to therefore doubt his loyalty to the rebellion. Bowie was one of the rebellion's best-known firebrands and had just taken San Antonio from the Mexicans.
Plot hole: The morning of the final battle, the sun rises behind the mission, silhouetting a sentry. When the ending credits roll, the sun sets behind the mission.
Other mistake: During the final assault, a man falls mortally wounded on a cannon wheel and shouts for Crockett to come over. Crockett is standing doing nothing with Beekeeper, in an action in where the defenders are largely out numbered. Shouldn't every man be fighting not standing around watching?
Factual error: When the scout comes in and describes a huge cannon the Mexicans have, there are actually two mistakes, one of continuity and one historical. The continuity mistake involves the powder horn the scout is wearing. When you first see him it is facing with the tip one direction. The scene then cuts to Bowie. When it cuts back to the scout again the powder horn is turned the opposite direction. The historical mistake involves the cannon itself. The largest cannon used in the battle was in possession of the Alamo defenders. Santa Anna brought only small field pieces on the winter march from Mexico.
Factual error: The last we see of John Wayne is when, mortally wounded, he lunges into the powder magazine with alighted torch and blows it up. In actuality, this was attempted by an Alamo defender named Robert Evans who was shot dead in the process of unsuccessfully trying to do just this.
Plot hole: At the start of the final battle, the Mexican artillery is lined up wheel to wheel, and fires the opening salvo. Apparently Newton's third law doesn't apply in Texas, because none of the cannon recoil after firing.
Factual error: Travis never took his orders from Houston, and Bowie never took his orders from Travis. Colonel Neill (not Houston) left Travis in charge at San Antonio while he went on a 20-day furlough to be with his family - not to go north with Houston (since Houston wasn't there to begin with). Travis then rashly asked the militia to elect a leader, and they chose Bowie. Eventually the two agreed to share command, Travis over the regulars and the volunteer cavalry, Bowie over the garrison volunteers. By February 24th, however, Bowie was very ill (probably with typhoid) and was bedridden for the rest of the siege, leaving Travis as the de facto commander. In the movie, he isn't confined to his bed until the final assault, and then as the result of a wound.
Continuity mistake: In the scene on the last assault on the Alamo, Mexican cavalry (in red coats) jump the palisade next to the chapel and are killed by a volley of musketry and their bodies are littered everywhere. Next time you see the area, however, the bodies have disappeared.
Continuity mistake: When Crockett's party first see San Antonio, they are carrying little more than blanket rolls on their horses - and no pack mules. However, when Crockett tells them to change into their best duds, top hats and other clothes appear from nowhere.
Factual error: Houston sent Bowie to San Antonio with orders to blow up the Alamo and withdraw to Gonzales. It was Bowie's idea (not Travis's) to stay and fortify the Alamo.
Factual error: The facade of the chapel is slightly anachronistic: the two upper windows were not added until the 1840's, and the top was more level - for the movie, it was deliberately distorted to suggest the famous hump by which people recognize the Alamo today. The chapel itself was built to scale, but the rest of the compound is about 75% as big as the original - otherwise, the Alamo compound is generally quite accurate.