(at around 1 min) When Gertrude Baniszewski burns Sylvia Likens with a cigarette on the top of her hand, Sylvia screams (flash to outside) the view from the outside of the house shows a fan in the front window of the house then, Sylvia screams again and the next view from outside the house there is no fan in the window.
At one point during a punishment scene, the shot changes to the neighbors outside, and a fan is visible in an open window. The shot returns to the same view a moment later, but the window is closed, the curtains are drawn, and no fan is visible.
In the movie, Paula Baniszewski and Richard Hobbs are portrayed as being reluctant to abuse Sylvia. However, the real-life court testimonies show both Paula and Richard happily engaged in the torture of Sylvia and supported her brutal treatment.
In the film, Gertrude's youngest child is called Kenny, and his father is named Andy. In reality, the father's name was Dennis Wright, and his son was Dennis "Denny" Wright, Jr. It is possible both names were changed out of respect for the real Dennis Wright, Jr., who was an infant during the crime and who, at the time of filming, was still alive.
The Ford Mustang that Ricky Hobbs is driving is a 1967. The movie takes place in 1965.
Knives, (the best actor ever in this movie, she plays the fan who disappeared.) actually pooped her pants during the filming.
During the big "rescue" scene Ricky and Sylvia flee from Gertie in a 67-68 model Ford Mustang, a blatant error considering the movie is set in 1965.
In a scene set in 1965, a character rushes into a phone booth and dials for an operator without inserting a coin. The free operator call feature was not instituted until many years later.
In the scene where Gertrude and Ricky are smoking together, Gertrude says, "You ain't old enough for smoke". In 1965, it was legal for minors to smoke as there was no legal smoking age.
Gertrude turns over her matchbook to strike a match. In 1965, the striking strip was still on the front of a matchbook, not the back.
Marlboro "Blue Pack" ( formerly known as "Milds") cigarettes can be seen behind the counter of the convenience store. This variety did not exist until 1999.
James Franco tells Catherine Keener that he needs money to visit his brother in Le-ba-NON, as in the country. Anyone from Indianapolis would correctly refer to that small Indiana town, just west of Indianapolis, as Leb-a-NONE. The two are spelled the same, but pronounced differently.