- Acting for Two: Alison Wright, who played Justine as an adult, also provides the computer voice, with the English accent, from the computer that Justine uses.
- California Doubling: Although the film was shot on location in Atlanta, Georgia, it is set in Plainfield, Illinois, with scenes in downtown Chicago, Illinois.
- Missing Trailer Scene: In the trailer, during the talk that Wolff's parents have with the Neurologist in the trailer he mentions, "Your son is a remarkable young man, it wouldn't surprise me if he has more in common with Einstein, Mozart and Picasso then he does with us.", this line is not in the movie.
- Sleeper Hit: The film had good word of mouth and grossed more than three times its budget. It also ended up #1 in disc and digital video rentals for the year 2017.
- Those Two Actors: Ben Affleck and J. K. Simmons, who play Batman and Commissioner James Gordon respectively in the DC Extended Universe. This is even more noticeable because their characters in this film have kind of a similar dynamic to the classic Batman-Gordon relationship, as Wolff is a supremely trained vigilante with a secret identity who helps law enforcement (Ray King) bringing criminals to justice.
- Uncredited Role: Allison Wright is uncredited for voicing the computer, even though it was more extensive than her on-screen time.
- What Could Have Been: This was originally envisioned with Mel Gibson starring, with The Coen Brothers directing.
Trivia / The Accountant