Múltiple

Inspiration for the film, real-life multiple-personality Billy Milligan (14 February 1955 - 12 December 2014), charged with three rapes, was the first person diagnosed with multiple personality disorder to use an insanity defense by reason of that disorder, and also first to be acquitted thus. Milligan had 24 personalities, consisting of 10 Desirables: Billy Milligan, Arthur, Ragen Vadascovinich, Allen, Tommy, Danny, David, Christene, Christopher, and Adalana; and 13 Undesirables: Phil, Kevin, Walter, April, Samuel, Mark, Steve, Lee, Jason, Bobby, Shawn, Martin, and Timothy; and The Teacher, a fusion of all of the other personalities.

In the close-up shot of Dr. Fletcher's degree scroll from Tulane University, the school of political sciences is misspelled as "political scineces". In addition, her degree of Master of Psychology would not be awarded by a school of political sciences.

The end credits are shown in 24 frames in the background of the scrolling credits to simulate the 24 different personalities that Kevin has in the movie.

Edited into Honest Trailers: Split (2017)