Toni Collette had told her agent that she didn't want to do any more heavy, dark films and only wanted to do comedies, but she loved the "Hereditary" script so much she couldn't turn it down.
Ari Aster requested that Alex Wolff and Milly Shapiro go out to eat in character a few times, and they would sit for up to three hours in silence while Milly wouldn't speak and Alex would try to get her to talk.
Toni Collette has called Ari Aster the most prepared director she's ever worked with. She praised him for practically having the full movie already shot and edited in his head two years before they started filming.
Ari Aster liked Utah for the film because he thought its mountains are beautiful and breathtaking, but also menacing and ominous.
Ari Aster wrote detailed biographies and backstories for all of the characters before even writing the screenplay.
Ari Aster: (at around 1h 23 mins) the voice on the phone calling Annie about her exhibit date at the Archer Gallery.