The character Steven is named after Steven Spielberg.
Amblin Television, the TV arm of Steven Spielberg's Amblin Entertainment production company, coproduced "The Haunting of Hill House." Flanagan said that the character Steven Crain, played by Michiel Huisman, was named after Spielberg, who produced the 1999 film, "The Haunting," an adaptation of author Shirley Jackson's 1959 novel that the show is inspired by.
"His love for the material is one of the reasons I was brought in at all to pitch for it," Flanagan said of Spielberg.
Flanagan said that Huisman was the first actor cast for the series, so when casting the other characters, whether or not they could pass as siblings of Huisman was taken into consideration.
Flanagan added, "From the jump, this was always going to be something different. I anticipated that Jackson fans would have mixed feelings about that. But I hoped we could at the very least honor her source material that did something different with it. I've heard it described as an 'echo' of the novel rather than an adaptation."
Flanagan said that the character Shirley Crain, played by Elizabeth Reaser, was named after Jackson.
One of the biggest twists of the series was hidden in plain sight.
In an early scene of the first episode, "Steven Sees a Ghost," a ghost moves from the shadows over the young Nell Crain's bed. The ghost is the "Bent-Neck Lady," which is revealed later in the season to be the adult Nell's ghost haunting her past self.
Flanagan said that the Bent-Neck Lady was part of his initial pitch for the series and that she is played in this scene by the adult Nell actress, Victoria Pedretti.
"She was painted dark blue so that she could blend into the shadows," Flanagan said. "She looked like an evil smurf with the lights on. We had a robust debate about whether people would recognize her."
He continued, "We had to be very careful to show enough of her to give us that first scare that would hook viewers, but not so much that we gave away the biggest twist of the season — the identity of the Bent-Neck Lady, which was the heart of my entire pitch for the show. Protecting that for the first five episodes was actually really difficult."
A key scene in the pilot was originally in episode five.
A scene in the first episode, when the young Nell (played by Violet McGraw) is laying on a couch and sees the Bent-Neck Lady above her, was originally in episode five. But it was moved to the first episode because it needed another "scare," according to Flanagan.
"An unfortunate thing that happens when you are trying to do genre work, whether it's a feature or television show, is trying to make sure you have enough scares metered out that the genre fans will be happy, and also trying to spend enough time developing your characters, which is a really difficult balance to strike," Flanagan said. "In this case we felt that we were one scare too light at this point in the pilot, and so we pulled that whole sequence up from episode five with the idea that we would see enough of it here that we could see the conclusion of it in episode five and still feel like we've seen something new."
Flanagan added, "That kind of post-production always happens in movies, but in television it's a whole other thing because you're pulling threads that run through 10 hours. The season was a house of cards. I would find all the time that it built on itself ... it was a lot to keep track of."
Victoria Pedretti submitted a self-tape that worked its way up to the casting director.
"We looked at a lot of actors for Nell and got hundreds of auditions for it," Flanagan said. "But we never really found that moment where we said, 'oh my god, it has to be her.' And that thing happened happened in Hollywood that you always hear about but never really see."
Flanagan said that Pedretti submitted a self-tape that worked itself up the studio chain.
"She had just graduated college, she'd never booked a job, she had an empty resume, and I don't even think she had a current headshot," Flanagan said. "But she had taped an audition herself and submitted it through her agency. These tapes come in all the time and they usually wind up at the bottom of the pile with the casting director."
Flanagan said the tape "did what it's supposed to do," and "bubbled its way up through every person involved in casting."
"It found its way to my casting director, Anne McCarthy, and she called me at 11 o'clock one night and said 'you have to watch this, I think this is Nell,'" Flanagan said. "And I said, 'are you sure, there's no resume here?' But a minute into her self-tape I knew she was Nell and that she was a star. And I realized that if we didn't cast her in this then someone else would scoop her up very quickly."
Flanagan said that every episode features hidden ghosts and that actors were "on standby" for every episode.
For instance, when the young Hugh Crain (played by Henry Thomas) is running through the house carrying the young Steven (Paxton Singleton) in episode one, there are ghosts hidden throughout the house, in the shadows and in the background, that are hard to spot unless the viewer watches it again.
"We would hide ghosts in plain sight in every episode," Flanagan said. "We have dozens of them in every episode ... that was one of my favorite ideas about the original pitch that I thought would be really fun."
"Ghosts" were on set every day of shooting the first season, but there was no guarantee they'd actually be working on any given day.
"We would call [the actors] early in the morning and they would go through makeup and be on standby, basically hanging out at craft service scaring anyone who went to get candy bars," Flanagan said.
"We'd spend 15 or 20 minutes before camera rehearsals trying to find a place to hide our ghosts," Flanagan added. "We did that every day. Sometimes it would work, but the big test was whether we could see them clearly if we were looking but would blend in. Sometimes we would look at them and think it was too obvious or too subtle and we wouldn't use them. But every single day that we rolled cameras at the Hill House, we had ghosts standing by that were ready."
Flanagan said the same people were used "again and again" because "not many people are willing to do that much makeup and sit around all day on the off chance that they'd be used in a shot in which the audience is not meant to see them. That's a tough sell for an actor."
"However many [ghosts] you think you found, whether it's true or not, I will always say there's one more," Flanagan said.