Netflix's horror series "The Haunting of Hill House" arrives on Blu-ray and DVD on October 15 with three extended episodes that feature commentary from director Mike Flanagan.

Business Insider watched the first extended episode.

Here's what we learned from Flanagan's commentary, from a Steven Spielberg connection to the series' hidden ghosts.

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Warning: This post contains major spoilers for "The Haunting of Hill House."

The follow-up to Netflix's horror anthology "The Haunting of Hill House," called "The Haunting of Bly Manor," is expected to debut in 2020. But fans of the last year's first installment can rewatch it while they wait for the show's return, only this time with added scenes and commentary from series director Mike Flanagan.

"The Haunting of Hill House" arrives on Blu-ray and DVD on October 15 and includes three extended episodes with commentary from Flanagan. The extended episodes include episode one, "Steven Sees a Ghost"; episode five, "The Bent-Neck Lady"; and episode 10, "Silence Lay Steadily."

READ MORE: Netflix's 'The Haunting of Bly Manor' is filling out its cast with actors from 'The Haunting of Hill House'

It also includes additional commentary for episode six, "Two Storms," which was shot in a series of long takes.

"The Haunting of Hill House" was a hit with critics and audiences last year. It has a 92% critic score and 91% audience score on the review aggregator Rotten Tomatoes.

"Over 10 episodes, it's stylish, moving, and sinister, riddled with ghosts both literal and metaphorical," The Atlantic's Sophie Gilbert wrote.

Business Insider got our hands on an advanced copy of the Blu-ray collection and watched the first episode's extended cut with Flanagan's commentary. Below are the most interesting reveals.