Actress Fairuza Balk is actually a Wiccan in real life. Balk was also able to help the makers of the movie keep the storyline as realistic as they could, and was able to give them Wicca contacts to help them in areas she couldn't.
An official website of the film said: "The crew had to return to the location a second time to complete filming interrupted by several weird occurrences that even caused witch consultant Pat Devin to raise an eyebrow. As the fog rolled in at midnight, the four actresses used actual Wiccan rites and language to invoke powerful forces. Then, as Fairuza Balk's character Nancy attempts to invoke the deity Manon, a flock of bats hovered over the set and the tide rose dramatically, extinguishing the circle of candles. Witchcraft consultant Devin recalls that 'Manon, a fictitious creation for the film, sounds very close to Mananan, the Gaelic god of the sea. Luckily, we weren't all swept to sea!'" Director Andrew Fleming is quoted: "'Every time the girls started the ceremony, and only when they would start the ceremony, the waves would start coming up tremendously fast, pounding heavily. Then, right when Nancy says her line, "Manon, fill me," right at that exact moment, we lost power. It was a very strange thing.'"
Andrew Fleming states in the DVD commentary that a PG-13 rating was sought. They followed all of the guidelines to earn that rating, but in the final outcome the film was rated R because the film dealt with teenage girls using witchcraft.
While researching The Craft, Fairuza Balk became familiar with Panpipes Magickal Marketplace in Hollywood, eventually buying the store and continuing to operate it until 2001 when she sold it to Jymie Darling and Vicky Adams, whom she had brought in as managers after her own purchase in 1995.
The shots of Nancy being covered in bugs were created by wrapping a life-cast of Fairuza Balk's head and torso in green screen material. The bugs were filmed crawling all over the casting and then digitally composited on top of a live action plate of Balk.
The text of the book "Invocation of the Spirit" that Nancy reads from in the magic shop comes from "The Book of Ceremonial Magic" by Arthur Edward Waite, a well-known occultist. The book does discuss invocation of spirits, although it is not the focus of the entire book as implied in the film.
Though the song "How Soon is Now" was originally perfomed by The Smiths, Love Spit Love did the cover for the Soundtrack. The Love Spit Love cover of "How Soon is Now" was also the theme song for the WB show Charmed (1998). Charmed, a popular TV show which ran for 8 seasons (1998-2006), is also about witches.
After Sarah returns to her house near the end, the house is full of snakes, rats, maggots, etc. As she retreats to the upstairs bathroom, we see her pass a whiteboard with the name Gustav Klimt, an artist whose works were denounced for their eroticism. He was also known to have a common theme of the "Femme Fatale" or women who were empowered and strong.
Although the name of the Catholic high school is shown as St. Benedict's in the film, it was called St. Bernard's Academy in the film's trailer. This is a nod by writer Peter Filardi to Saint Bernard High School in his southeastern Connecticut home town.
One of the first films to use Kodak's EXR 200T 5287 film stock. Cinematographer Alexander Gruszynski had been planning to use it sparingly, but liked it so much during tests that he decided to shoot most of the film with it.
Holly Marie Combs was in the running for the role of Bonnie. Had she been cast, it would have reunited her with Dr. Giggles (1992) costar, Cliff De Young. Ironically, Holly Marie Combs would eventually star in Charmed (1998), a TV series also about witches.
In 2017, Andrew Fleming stated that Charmed (1998) actually ripped off this film. Fleming revealed he actually wrote a pilot based on the movie for Fox which The WB was also strongly interested, and that it was his idea to have "How Soon Is Now" as title theme. The pilot was not picked up and the following year, "Charmed" premiered. Furthermore, Robin Tunney stated the rip off was "completely obvious to the point that people would think I was on 'Charmed' for years after."
The trivia items below may give away important plot points.
In the shooting script, as well as early edits of the film, it is implied that only Sarah has actual magic powers, and that the other girls' abilities are merely a result of their leeching off of Sarah's magic.
In the scene as the four girls enter on to the beach to invoke the spirit they each carry an animal familiar that represents themselves or their wants. Rochelle carries a clown fish - her hobby is diving and the pool is featured where her bully Laura-Lizzie bullies her. Bonnie carries a butterfly - it represents beauty this is in reference to her scars. Sarah carries a budgerigar - a budgerigar is also related a "Love bird" which is what she wanted Chris to be in love with her. Nancy is a snake - A snake is rebirth and renewal as Nancy wanted a better life for herself and her mother including power and being a leader.
During the sermon where Sarah's love spell starts working, Nancy's fate is foreshadowed by the priest's sermon about Adam and Eve eating from the Tree of Knowledge - "do not try to even know what only God knows. The moment man thinks himself the equal to God he is lost."
Mirrors are a repeating motif in the second half of the movie - Rochelle's reflection turns away from her when she sees the harm her spell has caused, Sarah uses a mirror to stop Bonnie and Rochelle from checking on her, Sarah uses a mirror to hide from Nancy, and during the fight Sarah sends Nancy flying into a mirror which shatters and knocks Nancy unconscious.
After Sarah has invoked the spirit, she starts to repeat the binding spell on Nancy. Nancy attacks Sarah with a knife, but doesn't actually hurt her despite literally sitting on top of her. This implies that Sarah's binding spell is partially working already.