Goofs

When the front of the mansion is shown, CGI is used to depict the 7-story tower that existed on the mansion in 1906, and the colors of the mansion are changed from their current (2018) colors, yet the final (1922) configuration of the mansion's main facade is shown. In 1906, the facade was quite different, as construction between 1906 and 1922 changed the mansion drastically. When overhead shots of the mansion rooftops are shown, the current (2018) colors are visible, and there is no sign of the 7-story tower (it was torn down after the 1906 earthquake) even though the spot where it should protrude is shown several times.

It is clearly stated in the middle of the film that the mansion's bell is rung only at midnight. Yet the bell inexplicably rings after the occurrence of the 1906 San Francisco Earthquake, which historically happened at 5:12 AM local time. After all characters make it out of the mansion, post-earthquake, it is still completely dark outside. Sunrise in San Jose, California on April 18th (the date of the earthquake) occurs around 6:30 AM PDT, which would've been around 5:30 AM in 1906 (prior to the establishment of Daylight Savings Time). The characters gather in front of the mansion, which faces east, so the sun should have been rising already (or at least about to break dawn, depending on how long the story's climax was supposed to have lasted).

A large portion of the movie has to deal with the famous Winchester lever-action rifle being used during the American Civil War. This is factually wrong. The first Winchester lever-action model did not appear until after the war, in 1866. The similar-looking Henry rifle and the Spencer rifle were the main repeaters used during the war, and even then repeating rifles were themselves rare on the average Civil War battlefield. Most troops used then-traditional single-shot weapons, primarily "rifle-muskets."

The film is set in 1906. Sarah Winchester's niece Marion Marriott left the Winchester mansion before 1906 to get married; she would not have been the one bringing Price up to speed.

The massacre at the Winchester Repeating Arms office never happened.

There is no record that Sarah Winchester ever visited a spiritualist.

Winchester Repeating Arms began to branch out into household goods nearly 20 years after the movie is set, and it's unlikely Sarah Winchester had a part in those decisions.

41:08 Into the movie you can see a reflection in one of the windows of the Winchester Mystery House which reveals the present day Splunk building across the street on South Winchester Blvd., San Jose, Calif.

In one scene, Price is writing on a notepad. However, upon closer inspection, he is simply tracing over already-written words.

In 1906 Dr. Price presents his "house guest" with a 1917 two dollar bill.

The movie is set in 1906. Marion tells Price that her aunt's house is "state of the art". This expression did not come into use until 1910.

When the mansion's exterior is first shown in daylight, the sun is depicted as coming from the right side of the frame when the camera is facing the mansion's front facade. This is impossible, as the mansion's front facade faces due east, and the right side of the frame would be north. In San Jose, California, which is in the temperate zone of the Northern Hemisphere, the sun cannot shine on the north side of the mansion.