The mountain is called Pendle Mountain after Pendle Hill in England. In 1612, twelve people from the area around Pendle Hill were tried for witchcraft. Also, Mother Malkin was most likely named after Malkin Tower, the house where Demdike (one of the witches tried in the Lancashire Witch Trials in 1612) lived. Malkin was local slang for excrement at the time.
Warner Bros. was originally supposed to release the film as part of a long-running partnership with the film's producer, Legendary Entertainment. Advertising materials were already being made when both parties agreed to end the partnership, and Legendary affiliated with Universal Pictures, which is now distributing the film. This explains why early posters still contain the Warner Bros. logo.
The original plan was that the soundtrack would have been composed by Tuomas Kantelinen and A.R. Rahman but due to the production delays they dropped out in autumn 2013. Marco Beltrami was then brought in to score the movie.
The title Seventh Son is also part of the title of an album and song by Iron Maiden called Seventh Son Of A Seventh Son. In the movie Jeff Bridges says "You're the seventh son of the seventh son" which is also similair to the chorus line in the Iron Maiden song. The album is a concept album.
Jeff Bridges and Olivia Williams have both worked with Arnold Schwarzenegger. Jeff Bridges had starred opposite Arnold Schwarzenegger in Stay Hungry (1976) and Oliva Williams had previously worked with Arnold Schwarzenegger on Sabotage (2014). A year after the film's release, Emilia Clarke starred opposite Arnold Schwarzenegger in Terminator Genisys (2015). Emilia Clarke and Kit Harrington star in HBO's Game of Thrones (2011).
Alicia Vikander would later go on to star as Lara Croft in Tomb Raider (2018). Olivia Wilde was rumored to play the role, but denied it. Olivia Wilde starred opposite Jeff Bridges in TRON: Legacy (2010) 4 years earlier.
Alicia Vikander would later go on to star as Lara Croft in Tomb Raider (2018). Kit Harrington's Game of Thrones (2011) co-star Emilia Clarke was rumored to play Lara Croft in the 2018 film before Alicia Vikander was announced.
Tom Ward bares a couple of similarities with Paul Atreides, the main protagonist of the best-selling science fiction fantasy novel "Dune" by Frank Herbert. Tom is the son of Mam Ward (a witch). Tom has visions. Tom has special abilities. Tom becomes a Spook and aids Master Gregory in battling Mother Malkin. Tom falls in love with Alice. Ma Ward is killed by Mother Malkin and after Tom becomes the new Master when he completes his training and destroys Mother Malkin and avenges his mother.