The Winchester Mystery House is an actual mansion that is located in San Jose, California. It is believed to be haunted by the victims of the Winchester rifle. It is too a tourist attraction since 1923, a year after Sarah Winchester's death.
Very little of the filming took place in the actual mansion. The mansion's design in reality is extremely cramped, making filming very difficult. As such, most of the mansion's interior needed to be recreated on sound stages.
Sarah Winchester had severe, debilitating arthritis and had a series of short risers, only 3 or 4 inches high, in place of stairs as it was very painful for her to raise her foot more than a few inches.
The promotional image for the film of Helen Mirren sitting in the carriage in mourning clothes mirrors the only known photograph of the reclusive Sarah Winchester on the estate, which is seen on the tour of the mansion in San Jose, California.
Real-life Sarah Winchester constantly built and rebuilt the house for 25 years. The Winchester house has windows and doors in the floor, doors that open into walls or nothing, and stairs to nothing or into the ceiling. Its total surface is 4.5 acres (24,000 m²).
The first company Oliver Winchester (Sarah's father-in-law) owned was a men's shirt company (Winchester & Company) with his twin brother Samuel. In the 1860s, Winchester invested in Volcanic Repeating Arms Company that produced a revolver designed by Horace Smith & Daniel Wesson (yes, Smith & Wesson). When the company went bankrupt, he bought the company out and cleared the debt of $57,000.
Lionsgate bought the film and photography rights to the Winchester Mansion for this film. So now tourists are not allowed to take any pictures of the interior of the mansion, because a tourist photo would be in direct competition with a Hollywood movie.
"Ghost Dance," the 45th and last issue from Saga of the Swamp Thing (February 1986), written by Alan Moore, was inspired, like this film, by the Sarah Winchester's story about the house haunted by the ghosts of all the people who were slaughtered by her husband's family gun.
World-Renowned Parapsychologist/Paranormal Investigator Christopher Chacon conducted the only scientific investigation of the reported haunt phenomena of the Winchester mansion and property in the early 1990's which was sanctioned by the Winchester property owners.
Partly to avoid confusion with Supernatural (2005), featuring main characters Sam and Dean Winchester, the movie is released in some countries in its original title "Winchester: The House That Ghosts Built".
Sarah Winchester and her house are given their own chapter discussion in "Ghostland: an American history in haunted places" written by Colin Dickey in 2016. Historically, Sarah Winchester was living in a time that was uncommon and unusual for women to pursue architecture. She was never licensed. Instead, she practiced and experimented on her own house. When one project would prove to not work out or she would lose interest a new project would be started. Even the projects that were completed will have an off-kilter appearance due to space constraints. It is easier to continue building and expanding the size of various parts of the house and within the house than to tear it out to start over.
The trivia item below may give away important plot points.
In the movie Sarah Winchester claims that 13 nails are necessary to retain the ghosts in their respective rooms, nailing a wooden piece in the door. It is a nod for the real life Sarah Winchester, who was obsessed with number 13: her house has 13 candles and wall clothes hooks are in multiples of 13; a spider web-patterned stained glass window contains 13 colored stones; and the drain covers on the sinks have 13 holes. In Sarah's tribute, the house's groundskeepers have created a topiary tree shaped like the numeral 13 and every Friday the 13th the large bell on the property is rung 13 times at "1300 hours" (13:00 PT, 1:00 PM) in tribute to her.