In episode 9, an SAS soldier says that Bokken Castle reminds him of a ghost story about "the end of World War II, and a castle in Transylvania, and the devil that lived there." This is a reference to the F. Paul Wilson novel (and Movie) The Keep (1983). Incidentally, there is a character in the episode named Paul Wilson. William Morgan Sheppard, who voices Farguson, also played in The Keep (1983) as Alexander, the caretaker of the keep.