Directed by: William Friedkin
Starring: Max von Sydow, Ellen Burstyn, Lee J. Cobb, Linda Blair, Jason Miller
Other mistake: When Karras throws himself out of the window, why is a man who needs a cane running full speed down those steep steps? It makes no sense since people use canes for balance.
Suggested correction: Some people have a cane as a fashion statement. Also, it's possible the cane helps but is not totally necessary, certainly able to be ignored when rushing to an emergency.
Continuity mistake: The Psychiatrist that hypnotizes Regan is wearing a tie that in the close-ups, is retied differently as the scene progresses. (01:02:05)
Demon: I'm not Regan.
Father Damien Karras: Well, then let's introduce ourselves. I'm Damien Karras.
Demon: And I'm the Devil. Now kindly undo these straps.
Father Damien Karras: If you're the Devil, why not make the straps disappear?
Demon: That's much too vulgar a display of power, Karras.
Trivia: The vomit that Linda Blair spewed was actually split-pea soup. Specifically, the effects crew decided to use Anderson's split-pea soup because Campbell's split-pea soup wasn't green enough.
Question: What is Chris McNeal's assistant listening to on the radio when Father Merrit arrives?
Answer: When it cuts to Chris MacNeil's PA, Sharon, listening to the radio it's only for about 20 seconds, and all we hear is a voice which presumably belongs to a random radio host or guest who is in the midst of offering motivational advice. This short scene serves to show Sharon's tension with what's going on in the house.