In keeping with the Halloween setting several character names allude to the horror/ mystery genre. Victor Clerval combines Victor Frankenstein and his friend Henry Clerval. Madeleine Escher and her boyfriend Roddy Allen are references to Edgar Allan Poe's "Fall Of The House Of Usher", in which Madeline Usher appears to obsess Roderick, her brother. "Ligeia" is a story by Poe which also features Rowena Trevanion. Van Tessel evokes Katrina Van Tassel in Washington Irving's "Legend of Sleepy Hollow". Jonathan Corwin was an important inquisitor in the Salem witch trials. Ken Strickfaden was a film effects designer, notably on the iconic laboratory sets for Frankenstein (1931) and Bride of Frankenstein (1935).
To sum up the unfortunate events of this episode, Lewis uses the proverb "For the want of a nail". This phrase appears in the first sentence of an elaborate English proverb stemming from the Middle Ages: "For want of a nail the [horse]shoe was lost. For want of a shoe the horse was lost. For want of a horse the rider was lost. For want of a rider the message was lost. For want of a message the battle was lost. For want of a battle the kingdom was lost. And all for the want of a horseshoe nail." The meaning of which is that one minor event has major consequences such as the plot of this episode.
Near the beginning, Laura Hobson receives a call from her friend Ellen, who asks, "When shall we three meet again?" This is the first line of Shakespeare's "Macbeth", spoken by one of the three witches, known as the 'Weird Sisters'. Alec Pickman later refers to Laura, Ellen and Ligeia by that title.
The line "We belong dead" is a quote from "The Bride of Frankenstein".
In addition to the various references to classic horror stories and films already noted, this episode also features the character names "Renfield" (from "Dracula") and Pickman (from H.P. Lovecraft's story "Pickman's Model"). A nursing home name includes the word "Holmwood", which is another character name from "Dracula".