The statuettes of the directors in the introduction of each episode were sent to the directors themselves after filming was finished.
Guillermo del Toro introducing each episode is a tribute to director Alfred Hitchcock, who introduced each episode of his anthology shows The Alfred Hitchcock Hour (1962) and Alfred Hitchcock Presents (1985) (Hitchcock died in 1980, so the latter used archive footage).
Episodes 5 and 6, Pickman's Model (2022) and Dreams in the Witch House (2022), are adaptations of short-stories written by H.P. Lovecraft, published in Weird Tales: "Pickman's Model" on October, 1927 and "Dreams in the Witch House" on July, 1933.
In Lot 36 (2022) Nick Appleton finds three rare occult books to summon demons named "Liber Primus: Daemonia", "Liber Secundus: Symvolia" and "Liber Tertius: Perilipsi". He is told by Roland about the existence of an another book named "Liber Quartus: Sacramentum". Translated from Latin it means "First Book: Demon", "Second Book: Symbol", "Third Book: Summary" and "Fourth Book: Sacrament".
Ben Barnes played Dorian Gray in the 2009 adaptation of Oscar Wilde's novel. Dealing with a painting with supernatural power that affects the protagonist just like Pickman's work in 5th episode.