There are several similarities between Jeremiah Sand and real-life cult leader Charles Manson. Like Sand, Manson was also a failed musician who reportedly took it very personally when his musicianship was insulted. Sand refers to his victims as "pigs," as did Manson and his followers. Psychedelic drugs were also used before acts of violence.
Late in the film, Red is engaged in a chain-saw duel with one of the cultists. The beginning of the battle, where each combatant shows off his chain-saw, bears resemblance to "Phantasm II", while the whole duel sequence is very likely an homage to "Texas Chainsaw Massacre 2".
The book Mandy reads early on during the film, "Seeker of the Serpent's Kiss", it's a prop, a fake book. It is actually the name of the musical composition playing during that scene and it is by the film's composer, Jóhann Jóhannsson.