The weather report playing on the television while Lavinia is washing dishes mentions Arkham, along with Innsmouth, Dunwich, and Kingsport. All these settings are part of different H.P. Lovecraft stories. In addition, Lavinia questions Benny about a former girlfriend from Aylesbury. It's another location that too belongs to Lovecraft's universe.
In a Q&A with Richard Stanley, he claimed that the film would be the first of a trilogy, with a Dunwich Horror adaptation coming next. Nevertheless, in March 2021 the trilogy was canceled after Stanley was accused of domestic abuse by his former partner Scarlett Amaris, and production company SpectreVision cut all relation with him.
The color used in this film to represent The Color is magenta, which doesn't exist as single wavelength of light as part of the spectrum of visible light (red, orange, yellow, green, blue, indigo, and violet; also known as "Roygbiv" to join the seven initials). Rather, it is an extraspectral color, that is only perceived by humans in a specific interaction of the optical rods in the eyes that detect red and blue in specific circumstances to create the magenta in the mind. Since red and blue are associated to evil and good, it means that The Color is apart from evil and good to come from another universe where these concepts cannot be applied. The color code for magenta is: RGB (Red-Green-Blue) 255, 100, 100; HSB (Hue-Saturation-Brightness) 255, 0, 255. The election of magenta to represent The Color is a hint for the previous The Color Out of Space (2010), a black and white movie where (at around 1h) The Color appears as little magenta bubbles and (at around 1h 11 mins) as uncountable magenta bubbles fusing to form The Color.
(at around 33 mins) When Ward Phillips walks around his tent at night looking for a possible intruder and he's suddenly dazzled by car lights, Ward covers his face with the book that he was reading, where can be seen the title "The Willows" and partially "ernon Blackwood" as author on the bottom of the book cover. It's refers the eponymous novel and an early horror story written by Algernon Blackwood and published in 1907, about two people having an otherworldly encounter while canoeing down the Danube. It's considered one of the best known of Algernon's works and an example of early modern horror connected within the literary tradition of weird fiction, and recognized as the main influence of a great number of later writers, including the H.P. Lovecraft, who considered it the finest supernatural tale in English literature.
Richard Stanley's favorite movie of Nicolas Cage is Vampire's Kiss (1988). He asked Cage to use the same style of performance.