The role of Sue Ann was originally written for a white actress. Tate Taylor modified the script to better suit an African-American woman after he showed the script to Octavia Spencer and she expressed interest in playing the role. The pair had previously collaborated on The Help (2011).
The sequence involving Sue Ann noticing the porcelain cat statues had been moved, is a homage to a similar sequence in Misery (1990).
The 3-legged dog that "Ma" walks in front of the liquor store is owned by a veterinarian that works at the clinic where all the interior vet clinic scenes were filmed.
Diana Silvers lied about her height and said she was 5'8" to get the role of Maggie, even though she is actually 5'10½".
Although not filmed in Ohio, there are several clues to indicate that the film takes place in NorthEast Ohio. First, all the local vehicles have Ohio license plates. Second, the prefix of the Hawkins Security number is 216, which is the area code for the greater Cleveland area. Third, a nuclear power plant is visible in the opening credits - The Perry Nuclear Plant is just 40 miles NorthEast of Cleveland. There are also several casinos in the Cleveland area.