Visible crew/equipment: When the ambassador and the photographer are in the cemetery getting attacked by the dogs there are men standing behind a tree. I'm assuming they're the trainers - they are located when the photographer is trying to hop the fence. Look in the back right hand corner - there are about two or three men standing there. (01:21:15)
Visible crew/equipment: When Peck is falling down the stairs with the kid, you can see the back pad through his coat.
Factual error: It is highly unlikely that a British police detective making routine enquiries would be carrying a gun.
Audio problem: When Thorn and Jennings are at the apartment in Italy they are talking about Bugenhagen and Jennings says that he is an exorcist and has read about him. However, his lips continue to move even after he has finished speaking. Although the camera is on Thorn and Jennings is blurred in the background, his facial movements are still easy to see.
Factual error: Keith Jennings refers to an astrologers' publication which describes a star "like the star of Bethlehem" but "on the other side of the world, the European continent." Bethlehem is not on the other side of the world from Europe, it's at the same longitude as eastern Europe and less than 800 miles from the European mainland. (01:00:20)StarryMessenger
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.