One of the trailers for Hereditary (2018) was accidentally shown at the beginning the PG rated family friendly film Peter Rabbit (2018) in Innaloo, Western Australia. It caused a small panic in the theater with parents fleeing the cinema with their kids. The theater eventually shut the screen off and offered every audience member a complimentary movie pass to apologize for the mistake.
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.
(at around 1h 6 mins) To make the chalkboard write on itself, the special effects team put a magnet in the chalk and put a magnet on the other side of the chalkboard to make the chalk move--it was very difficult to get a small magnet inside the chalk and make it write smoothly.
The producer said that it worked out well that Gabriel Byrne and Alex Wolff had worked together, and Alex and Milly Shapiro knew each other from school, because it made Toni Collette the outsider, which mirrored Annie's character and feelings of alienation within her own family.
The house was constructed completely on sets on a soundstage in Utah in order to follow Ari Aster's shot list. They needed to be able to remove walls and ceilings in order to shoot the rooms to look exactly like the miniatures.
(at around 14 mins) In Peter's first scene at school, the words "Escaping Fate" is on the chalkboard with the teacher discussing it. This is a reference to Halloween (1978), where the main character discusses the same thing in class. Appropriately, this movie was released the same day as the trailer for Halloween (2018).
Production designer wanted to play with the idea of "sacred geometry"--triangle (Annie, Peter, Charlie), square (introduces Steve's character, home, groundedness), circle (infinite, genesis, Ellen) - all different shapes embedded within the design of the set. If you look closely, the second floor hallway has squares and triangles carved into it.
Toni Collette also stars in the Showtime series United States of Tara (2009), featuring Toni as a woman with dissociative identity disorder trying to raise her children, maintain her marriage and discover why she may be suffering from DID.
(at around 20 mins) Disassociative Identity Disorder, the mental illness Annie claims her mother suffered from in the group therapy scene, is also the condition diagnosed on the lead subject in the movie Split (2016). The movies have the same producer.
The trivia items below may give away important plot points.
During the support meeting, Annie recounts her brother's suicide at age 16, and states that his suicide note blamed their mother (Ellen) for "putting people inside him." Though Annie chalks this up to his schizophrenia, it could very well be that Ellen originally attempted to conjure Paimon through her own son. His death (and her failure to summon Paimon) would then explain why Ellen put so much pressure on Annie to have children, and why Charlie stated early on in the film that her grandmother wished she was a boy.
(at around 1h 35 mins) In an interview, Alex Wolff explains that he wanted to actually break his own nose for the scene where his character slams his head into a desk. Director Ari Aster respectfully declined that offer and told Wolff they'd give him a soft, cushioned desk for the scene. When it was time for the scene to be shot, Wolff slams his head into the desk only to discover that the top was foam and the bottom was hard. He dislocated his jaw (which is a previous injury the actor has had) for the scene.
Hereditary's advertising campaign has been credited for keeping Charlie's death a secret from viewers, notably by showing Milly Shapiro prominently in the trailer, even though Charlie is alive for only one quarter of the film. This deliberate mislead is similar to the horror classic Psycho (1960), where Janet Leigh was made to look like the star of the film, only to be murdered one-third of the way through.
(at around 1h 20 mins) Throughout the film, several words can be seen scrawled on walls. At one point, there are two words, LIFTOACH PANDEMONIUM. Liftoach is an English transliteration of the Hebrew word 'To open', Pandemonium is Latin for All Demons and is what Satan names Hell in John Milton's Paradise Lost.
Annie's mother Ellen likely tried to summon Paimon through her son Charles before his suicide, which is why he claimed she was trying to put people inside of him and was misdiagnosed with schizophrenia. Charlie was the reincarnation of Paimon, and shared a similar name with her uncle.
(at around 1h 55 mins) Toni Collette wore a prosthetic neck and used a piano string for the scene where she saws her head off. It is made to look like a wire saw, which, due to its light weight and portability, is commonly carried by backpackers. Considering the locale, it would be reasonable to find such an item in an attic.
The script was originally written to take place in a snowy landscape in the mountains, but due to cast availability they had to shoot in May/June, so they decided to "embrace the green" and look at the lush, green, springtime as emblematic of the awakening and rebirth of the cult.
(at around 14 mins) In an early scene, the subject of free will is discussed while mentioning one of Sophocles' plays. In the same vein, Ari Aster states that the Graham Family has no free will on the events that are taking place. For Aster, the film is very Greek in that sense and the way things turn out is absolutely inevitable, the family has absolutely no agency. And that's where the dollhouses came in. Annie creates these miniature figures and dollhouses and they served as a perfect metaphor for the situation; they're dolls in a dollhouse being manipulated by outside forces. Any control they try to seize is hopeless.
(at around 1h 35 mins) In one of the scenes in Peter's classroom, the teacher is talking about the sacrifice of Iphigenia, Agamemnon's daughter. Both Iphigenia and Charlie are daughters who were sacrificed in hopes of bringing forth a great event; one being victory against the Trojans and the other the bringing forth of Paimon.
(at around 30 mins) During the party scene, just as Peter enters the bedroom to smoke pot, some kids are watching a black and white video on a laptop of someone being beheaded on a guillotine - foreshadowing the film's multiple beheadings.
At the end when the life-sized figurine of the demon Paimon is shown, the fingers of its right hand are positioned in a way that Jesus is often portrayed as doing in medieval paintings (pointer finger and middle finger out and together, other two fingers curled in a fist, and thumb parallel but slightly curved), but on Paimon, he's holding it upside down. The medieval and ancient hand gesture is used as a representation of Jesus, so like crosses being inverted, Paimon is using this to disrespect Jesus. Also, Paimon is wearing a halo with rays coming out of it like a sun. This halo is also seen in depictions of Jesus, thus meaning those worshiping Paimon believe he is the true savior.
(at around 4 mins) During her funeral speech Annie mentions that there are many strangers at the ceremony. It is later revealed that her mother was a cult member. The strangers at the funeral were members of the cult, some of whom can be seen in and around the house during the film's final act.
Hereditary is reportedly inspired by an apparent curse over Ari Aster's family that seemed to bring them bad luck over a three-year period. During a Q&A session, Aster himself only mentioned: "I had gone through some stuff with my family. I took my sickness and now put it inside all of you".
According to Ari Aster, with Hereditary, he wanted to make a film about the corrosive effects of trauma on a family unit and he also knew that he wanted to make a film that had sort of an ouroboros quality about a family that's basically eating itself in its grief. Ultimately, Hereditary is a film that was seriously tackling these issues and operating almost as a meditation on these things, while at the same time functioning as an exciting genre film that hopefully delivers.
For Ari Aster, the film itself is a running metaphor for family trauma and grief. It is operating all the way through and at the end, the movie is still about how trauma can utterly transform a person, and not necessarily for the better.
One of Peter's friends from underneath the bleachers can be seen at the end of the film as one of the town's secret cultists. When they are smoking at school, he is the character with a man bun and a hoodie. When the camera is slowly following Peter's feet in the treehouse, it pans over the kneeling cultist's heads. The closest one in frame is the man bun, still intact.
During the therapy session Annie tells of a troubled family history that she had largely kept to herself, because she did not want to "put more stress on the family". It is suggested that the family had been under the influence of the cult for a long time and hence that Annie was the one suffering for the longest time. During the film's finale, Peter gets to see with his own eyes what had been manipulating his mother all those years. The song playing over the end credits, "Both sides now," thematically relates to this series of events. The song contains the line "I've looked at life from both sides now" which could suggest that Peter was now able to see things from his mother's point of view. The song also contains the line "Tears and fears and feeling proud, to say I love you right out loud" which could suggest, that Peter finally understood that his mother actually did care for him and now was able to return those feelings, in spite of all he had been put through.
(at around 16 mins) Early in the film, Charlie cuts off an already-dead pigeon's head outside her school. This foreshadows Charlie's accidental decapitation, and the beheading of several other characters.
There are many clues, as to Peter being the one who will be the host for Paimon. Peter was the one who accidentally killed Charlie, Annie expresses constant fear and anger towards Peter (to the point where he asks Annie why she is afraid of him) and finally because Joan yells at Peter across the schoolyard, saying "I expel you" and "get out", obviously trying to get ahold of his body, so Paimon will be let in.
Hereditary shares several similarities with another A24 film, The Witch, in spite of having different writers/directors. Both films depict struggling families suffering from extreme grief and being targeted by Satanic cults, both were filmed near woods, and both end with the oldest child in the family being the presumed sole survivor and encountering the cults that harmed them.
When she first meets Joan, Annie talks about how she was sleepwalking and covered Peter and Charlie in paint-thinner, almost burning them to death. Later in the film, she accidentally burns Steve to death.
The use of a piano wire for Annie's self-inflicted decapitation is foreshadowed moments before by the piano being tipped onto its side in the living room while Peter surveys the scene of his dead father.