The pentagram is obvious in some scenes and not so obvious in others. Production designer Graeme Murray created rooms with five sides and had the plastic surgery unit with five operating rooms represent an imaginary pentagram.
Viewers ended up finding the nurse's name as an unintended reference to Rebecca Nurse, an innocent woman prosecuted during the Salem witch trials, and the Rider-Waite tarot deck, the most popular tarot deck utilized in the world.
This had some difficulty making it onto TV screens due to its high gore content.
During the scene that shows the Encyclopedia of Witchcraft and Demonology, the time on the clock reads 3:40. This is known as the Satanic witching hour.