The movie features a traditional Irish folk song, "The Tan Yard Slide". The rest of the songs, "Oh, Gallowgog", "Hymn of Gallowgog" and "Lord of Misrule (The Balad of Tobias Bron)" were created specifically for the movie.
The Lord of Misrule is not a creation for the movie but a Middle Age figure, also known as the Abbot of Unreason in Scotland and as the Prince des Sots in France. Usually he was villager or sub-deacon chosen to play the role, charged to lead the Christmas revelries. In the United Kingdom the festivity was abolished in 1541 by Henry VIII, later restored by the Mary I and finally abolished again by Elizabeth I, although it continued being celebrated in the towns for a time. In the 17th century, because the rising of the Puritan party and the Church of England, it was outlawed as it was considered disturbing. The origins of The Lord of Misrule remains unknown, but some historians have pointed that it could be in the Roman Saturnalia celebrated from the 17 to 23 December (in the Julian calendar), where a man disguised as false god Saturn led the festivity. It could be the ancestor of the later King of Carnival.
The movie is divided in four chapters, as the four parts of the harvest festival.
One motto of the pagan belief of the town prays "He stands in the fields and waits". It pays tribute to Niños diabólicos (1984), where a sect composed by murderer children created their own religion whose motto prays "He who walks behind the rows".
Second time that Ralph Ineson plays a man obsessed with religion in a horror movie, after La bruja (2015).