Factual error: The song that Davy Crockett plays on the violin is 'The Mockingbird Quick-Step,' written in 1855, several decades after the events of this movie (and later used by the 'Three Stooges' as a theme song.).
Continuity mistake: In the shot where Travis hands Seguin the third message to Houston the off-center seal is closer to Travis. As Seguin takes it the seal is closer to him. (00:56:15)
Continuity mistake: While one of his advisors tells Houston that some of the men from Gonzales have deserted to go to the Alamo, the advisor's hands change from clasped in front of him to on his knees. (01:06:55)
Continuity mistake: While planning the assault, one of Santa Ana's generals objects to attacking before the cannon arrive. He unclasps his hands twice. (01:33:40)
Continuity mistake: Crockett leads a handful of soldiers out to burn down the shacks around the Alamo. In the first shot a few soldiers are speeding up to walk past Crockett, and in the next someone has already passed him. (01:02:20)
Audio problem: When the Mexicans begin their final attack, we see Travis call to Joe to wake him up, but if you watch closely, you don't see his lips move, you just hear "Joe."
Factual error: A marker at the real Alamo says that Travis and Bowie blew up the buildings that day. David Crockett never left the Alamo.
Factual error: In reality, the chapel of the Alamo was much further back then what you saw in the movie. In fact, it didn't even border "Alamo Square", the large area of land in the middle of the surrounding buildings and walls. Instead, it had its own little square courtyard in front of it, and a small wall leading to the chapel's courtyard bordered "Alamo Square". In other words, the chapel itself was about 30 to 40 feet behind the rest of the walls and buildings.
Continuity mistake: When Houston and Bowie are drinking in the street at night, Houston skips from looking directly at Bowie to suddenly gazing into space between shots as he says, "Texas, wasted on the Texans." (00:13:00)
Factual error: In the scene where Houston is in Gonzales and when Guinan rides up to him, there is a shot of soldiers in the background and you can plainly see that one of them is wearing a pair of modern, zip-fly jeans.
Continuity mistake: When Travis leaves his son with the Ayerses, as he is turning to ride away, the man next to him mounts his horse in an instant. (00:15:20)
Audio problem: The messenger at the beginning leaps off his horse and says, "They're all dead. Alamo." Watch closely and you'll see his lips don't match "Alamo" and he keeps speaking without making a sound. (00:02:25)
Continuity mistake: After he divulges his illness, Bowie is hunched over when he unsheathes his knife, but he is sitting up straight when he offers it to Crockett. (00:42:10)
Continuity mistake: Houston leans on the table while he makes his offer to Crockett at the party, but is standing completely straight just before he walks away. (00:05:40)
Continuity mistake: Immediately after Santa Ana allows civilians to leave the Alamo, Crockett tells Travis to talk to the men. Travis switches between shots from having his hands raised cleaning his gun to lowered out of the frame. (01:19:50)
Continuity mistake: When Santa Ana is planning the assault with his generals, the tip of the map pointer switches from light to dark constantly. (01:32:55)
Factual error: The cannonball that Travis cuts the fuse off is way too big for the Mexican artillery. The largest cannon they had at the battle was an 8 pounder, meaning a ball about 4 inches wide. A cannonball as big as the one Travis carried would have been at least 100 pounds.
Other mistake: In the attack on the jacales outside the Alamo, a Mexican soldier is shot and crawling on the ground. Crockett asks him his name just as he dies. Later at the Battle of San Jacinto, the same soldier is shown sinking below the surface of Peggy's Lake as a Texican strangles another soldier with his musket.
Answer: The siege of the Alamo lasted thirteen days, so events would happen both day and night. The actual final assault began at around 5am, and took no more than ninety minutes - it was over by sunrise.