The theatre featured at the beginning of the film is the Redford Theatre, a historic Japanese style theatre with a fully functioning Wurlitzer organ, in the Old Redford neighborhood of Detroit, MI. The Evil Dead (1981) premiered there.
The dilapidated house that Hugh hid out in, and that Jay and her friends explored, is a house style called the American Foursquare. This style was popular from the 1890s through the 1930s. Many floor plans for the foursquare feature "circular" traffic patters, where one can proceed through several rooms and return to the starting point without ever reversing the path: kitchen, vestibule, living room, dining room, and kitchen, for instance. In some homes, adjoining bedrooms shared closets and bathrooms. This kind of "fluid" floor plan would make this style of house particularly desirable if an escape from "It" was needed.
The time frame of the movie is intentionally kept ambiguous so that it resembles a dream. Some of the cars shown are from more recent times. Many appear to be from the '60s to late '80s. Early CRT television sets are shown whenever the characters are watching movies. Conflicting technology include Yara on a device that looks like a shell compact, but she reads from it like an e-book reader and using it as a light source at one point. Also, the girl from the beginning of the film uses a cellphone and drives a modern automobile, with several modern vehicles in view.
The poem that Jay's English teacher reads out loud is T.S. Eliot's "The Love Song of J. Alfred Prufrock." The poem seems to share some commonalities with the film.
Jay is short for Jamie, a tribute to scream queen Jamie Lee Curtis. In the film, Jay has a sister named Kelly. Jamie Lee Curtis also has a sister named Kelly Curtis.
The film takes inspiration from several horror films and their tropes from the '60s to the '80s, especially from the slasher classic Halloween (1978). The girl in the opening scene of the film is named Annie, and one of Laurie's friends in Halloween (1978) was named Annie Brackett.
The film alludes to teenage problems through its props. This is seen when Jay is lining up blades of grass on her upper leg (cutting/suicide), as well as Jay's tray of food in her room that first has a pill laid out on a napkin, and later is the only thing touched from the tray (drug dependency).
The director David Robert Mitchell said in an interview that the 'monster' could potentially board a plane in order to follow the cursed person.
The entire score by Rich Vreeland ("Disasterpeace") was completed in less than three weeks.
Jay and Kelly's mother's face is never clearly shown. In the first scene in which she appears in the film she is seen talking on the phone in the kitchen with her face completely covered by her hair. In every other scene her face is either out of focus or partially cut by the frame.
Following overwhelmingly positive first weekend reception from critics and audiences, the film's originally-planned VOD/theatrical release was cancelled in favor of a theatrical-only release.
Disasterpeace recorded the score for the film because the director, David Robert Mitchell, was a huge fan of the video-game Fez (which Disasterpeace did the music for).
David Robert Mitchell has cited the works of George A. Romero and John Carpenter as major influences on his style of filming and creative decisions on It Follows (2014).
The final scenes of It Follows (2014) contain several allusions to death and the souls of the dead or ghosts as they are commonly known. In the hospital, Yara reads the following line from The Idiot, "Your soul will leave your body and you will no longer be a person." In the next scene when Jay and Paul walk down the street, the neighborhood is decorated with fake cobwebs and pumpkins, indicating that the scene takes place around Halloween. Halloween can be traced back to ancient traditions set to honor the souls of the dead. Jay is wearing a white dress and Paul is wearing a long white hoodie, both of them bearing a slight resemblance to popular depictions of ghosts. A "Dead end" sign is seen both in front of them and to their right. The man next to them is busy removing dead leaves. What can be seen of the inscription on Jay's cast reads, "Here lie the bones of Jay."
(At around 49:00) There are some high school campus announcements. One is in reference to wrestlers handing forms in to Mr. Dwiggins. This is a nod to the sound editor/re-recording mixer Christian Dwiggins.
David Robert Mitchell started writing the screenplay in 2011.
Cameo
Rich Vreeland: composer of the soundtrack; plays the announcer in the high school where Jay is searching for Hugh.
Spoilers
The film's concept derives from a recurring nightmare the director used to have, where he would be stalked by a predator that continually walked slowly towards him.
Mike Lanier, who plays the very tall "It", is a 7'7" Detroit resident who designs engines for General Motors and is one half of the world's tallest twins.
The director (David Robert Mitchell) said that neither a condom nor same-gender sex would stop the monster and the curse would still be passed.
The colors of red or pink are used to foreshadow the upcoming appearance of it as they appear either in the background or on a character's piece of clothing whenever it attacks.
In the beginning of the film, when the main character Jay is seen looking into the mirror as she gets ready for her date with Hugh, there are two photos on the mirror: one of Jay in the swimming pool and the other of her and her father. At the end of the film, "It" takes the form of her father and attacks Jay in the swimming pool.
Although the entire movie seems to be reminiscent of the '60s - '80s with no modern technology, Yara is seen several times with a shell-looking touch screen. It looks like a compact mirror, but we see she's reading something from it. Also Annie, the girl in the opening scene is shown calling her father on her mobile phone when she is sitting on the beach.
Early in the film when Jay's friends are watching a movie on the old TV you can hear the following lines from the movie loud and clear: "You're afraid of an overload. You can't tap enough electricity wherever you get it from to control a strong enough charge". Later in the film when Jay's friends plan to electrocute "It" in the pool, it turns out that they can't tap enough electricity to get a strong enough charge, and the plan fails.
A ball seems to follow the curse throughout the entire movie and soon after Jay gets infected, a ball hits her window and lands in her garden. When they go to Hugh's house they find a picture of him holding a ball. After Jay has slept with Greg a ball is seen bouncing from the direction of Jay's house towards Greg's house. Finally when Jay sees Greg dying, the motif on her T-shirt, a blonde girl and a ball, is seen clearly. The ball is covered by her hair up until the very moment he dies. She is still wearing the T-shirt later when Paul tries to kiss her implying that she did not go through with her plan to pass it on to the guys on the boat.
Jay's friends play "Old Maid" when she returns from her date with Hugh. The rules of that game are very similar to the rules of "IT" i.e. you have to pass something on in order not to lose. Moreover most of the specific cards being shown hold strong similarities to characters and events that are not seen until later in the movie. Thus the following cards are shown: "Cranky Kluck" (angry teacher), "Old Maid" (old lady), "Winnie Waite" (waitress), "Bikey Bess" (girl on bike) and "Bronco Buster" (cowboy with guns).
When Jay's friends play "Old Maid" (the card game played on the porch), there is a slow zoom in on a card that has a cartoon of an old lady on it. This foreshadows the next scene when Jay first sees "It" follow her in the form of an old lady.
The paddling pool in Jay's garden is depicted as a pleasant and safe place and the kids have several pleasant memories from their childhood involving water. In the present however, "bigger pools of water" like lakes, oceans and public swimming pools all seem to be associated with danger and "It". The first girl is killed on the shore of a lake. Jay and Hugh are sitting on the shore of a lake just before he passes the curse on to her. In the classroom, just prior to the appearance of the Old Maid, the camera pans across the cardboard where the text "required reading, The Old man and the sea" is written. Later, when Jay faces the peeing woman in the kitchen, three paintings are seen just before the attack - the first one, depicting a roaring ocean, is seen when Jay is talking to Paul on the couch, and the other two, both depicting lakes, are seen as she walks into the kitchen. In the same scene, the movie playing on the old TV shows a blonde woman in the ocean being attacked by a monster. The subsequent attack by the small boy takes place in the beach cabin near the shores of a lake and the final attack by Jay's father takes place in a big public swimming pool.
Someone (or something) in the distance appears to still be following during the final scene of the film.
Yara reads out a section from Fyodor Dostoevsky's novel The Idiot, which sums up the "But here I should imagine the most terrible part of the whole punishment is, not the bodily pain at all-but the certain knowledge that in an hour,-then in ten minutes, then in half a minute, then now-this very instant-your soul must quit your body and that you will no longer be a man-and that this is certain, certain!"