Many cast members have worked with director Mike Flanagan before (some several times): Carla Gugino, Henry Thomas, Kate Siegel, Lulu Wilson, Annabeth Gish, Samantha Sloyan, James Flanagan, Elizabeth Reaser, Catherine Parker and James Lafferty have all appeared in Flanagan's previous films. In fact, there is at least one person from every single film Flanagan has made prior to this, going all the way back to Absentia (2011).
Carla Gugino and Henry Thomas previously worked together in Gerald's Game.
Stars Carla Gugino and Oliver Jackson-Cohen previously worked together in the movie Faster (2010)
The series is based on the 1959 novel of the same name by Shirley Jackson.
Henry Thomas (young Hugh Crain) wore blue contact lenses through the entire season. The elder Hugh Crain (played by Timothy Hutton) has gray eyes. Hugh enters Hill House a wide-eyed house flipper who never faced a problem he couldn't fix. As time passed, Thomas' bright blue eyes turned into Hutton's steely gray, as the elder Crain has pulled himself away from his children and the events that haunt him to this day.
The series premiered on Netflix on October 12, 2018.
The Amblin logo at the end of each episode features the silhouette of E.T. riding in the basket on Elliott's bicycle flying in front of the moon from the 1982 movie, E.T. the Extra-Terrestrial (1982). Elliott is played by Henry Thomas (young Hugh Crain).
In the first episode, when young Luke (Julian Hilliard) is playing in the tree house, he has an E.T. metal lunchbox in front of him. On the lunchbox is a portrait of Henry Thomas, who plays a young Hugh Crain on the show.
Mrs. Dudley explains to Olivia Crain her rule about not staying in Hill House late 'We don't stay after dark, Horace and I' 'I would work in the daylight, it's very different in the night, it's different in the dark'. A similar line can be heard in the Haunting films where Mrs. Dudley explains to Eleanor (Nell) 'I don't stay after I set out the dinner, not after it begins to get dark, I leave before the dark, 'so there won't be anyone around if you need help, we couldn't hear you, no one could, in the night, in the dark'.
In the basement scene in episode 7, a girl can be seen in several background shots. Just as Hugh (Henry Thomas) is about to discover what's hidden behind the brick wall, you can see her standing in the back against the wall to his left. She also leans into the shot as Hugh leans towards the opening in the brick and she is there a 3rd time in the next scene behind the police officers. There are many other hidden people or ghosts throughout each episode within the house.
Carla Gugino plays the mother of young Theo in this series, however Kate Siegel who plays the older Theo in this series was the mother of Carla Gugino's character in Gerald's Game (2017).
Kate Siegel discovered she was pregnant shortly after filming started. She battled pregnancy symptoms throughout the shoot, including severe morning sickness towards the end of filming.
In the first episode the Lasser Glass from Oculus (2013) can be seen on the wall of Hill House while Nell (Violet McGraw) is dancing through it. Both Oculus (2013) and The Haunting of Hill House (2018) are directed by Mike Flanagan.
Mike Flanagan, the director of the show, is married to Kate Siegel, who plays Theo. She has also starred in his other films including Hush and Gerald's Game.
Elizabeth Reaser (Shirley Crain) and Samantha Sloyan (Leigh Crain) both starred in Grey's Anatomy and love interests for Alex and Callie.