Niklas Kvarforth (Sven) is the vocalist of Swedish Depressive Black Metal band Shining. The band's logo can be seen in the movie on the back of Sven's laptop.
The Leviathan Cross, or Satan's Cross, can be spotted at several places in the mansion. It was originally the alchemical symbol of sulfur but was later adopted by Anton Szandor LaVey, the founder of Church of Satan, as a satanic symbol.