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)
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."
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.
Tailkinker ★