Trivia: The smile that Damien gives at the very end wasn't scripted. Originally, Damien was supposed to "look really mean," but Harvey Stephens couldn't keep a straight face: he started to smile, then laugh. Richard Donner decided that the smile made Damien look even more evil, so it stayed in the movie.
Trivia: The assault takes place on Precinct 9, Division 13. There is no "Precinct 13" in the film. At first John Carpenter wanted to call the film "The Anderson Alamo" (the original title of his screenplay), and at one point he changed the working title to "The Siege." CKK, the film's distributor, was responsible for the misnomer; it rejected Carpenter's titles and came up with the name "Assault on Precinct 13" (which it felt was more ominous sounding) during post-production.