- Creator In-Joke:
- Dawson Casting: Inverted. Nell is shown to be 32 when she dies, but the actress was 22 during filming. Presumably because she dies early on and is shown more times in flashback, so casting a younger actress is necessary.
- Fake American: Michiel Huisman is Dutch and Oliver Jackson-Cohen is British playing American siblings. Both hide their accents pretty flawlessly.
- Production Posse: Mike Flanagan is again working with wife Kate Siegel (whom he worked with on Absentia, Oculus, Hush, Ouija: Origin of Evil, and Gerald's Game) and a plethora of frequent collaborators. There's Carla Gugino (Gerald's Game), Elizabeth Reaser (Ouija: Origin of Evil), Henry Thomas (Ouija: Origin of Evil, Gerald's Game), Lulu Wilson (Ouija: Origin of Evil), Samantha Sloyan (Hush) and Annabeth Gish (Before I Wake).
- Real-Life Relative: Kate Siegel (Theo) is married to director Mike Flanagan.
- Remake Cameo: Russ Tamblyn plays Dr Montague. He had played Luke in The Haunting (1963).
- Separated-at-Birth Casting: Not only do the Crain siblings look like they could really be related and the offspring of Olivia and Hugh, but for the most part, they also have uncanny resemblances to their child actors.
- The character Shirley who did not exist in the book is of course named after author Shirley Jackson.
- Harris Funeral Home is named after Julie Harris, who played Eleanor in The Haunting (1963).
- What Might Have Been: The series director Mike Flanagan revealed that the story was originally planned to have a much darker ending. It would have played out basically the same, except during the shot of the entire family celebrating together, the window of the Red Room would have been in the background, implying that they never managed to actually escape the house. He realized that he had become too attached to the characters and wanted to give them a proper happy ending, so rewrote the story so they actually did escape.
- Word of God:
- The creators confirmed that the five Crain siblings are meant to represent the five stages of grief, from oldest to youngest. Steven is Denial, Shirley is Anger, Theo is Bargain, Luke is Depression and Nell is Acceptance.
- It was also confirmed that the person who put button on Nell's eyes was Olivia, since Olivia knew how much Nell loves buttons.
Trivia / The Haunting of Hill House