Jonah Hex's ability to bring the dead back to life and speak to them is confined to the film only. He does not possess this ability in the comic books.

In an anecdote on The Tonight Show with Conan O'Brien (2009), Josh Brolin revealed that he broke and repaired John Malkovich's thumb while shooting a fight scene.

Michael Fassbender based his character on sociopaths like the Riddler (Edward Nygma) and A Clockwork Orange (1971) villain Alex DeLarge.

The dog had to spend an hour in the make-up chair to get his mongrel look.

During the duration of filming, Josh Brolin could only shave off half his beard to accommodate the prosthetic on the other side of his face. This meant he spent several months walking around with only half a beard on his face.

Josh Brolin initially hated the script, but later changed his mind, growing to like its tongue-in-cheek tone.

Josh Brolin later admitted that the film became unsalvageable due to its troubled production, but insisted that everyone involved, cast and crew, had sincerely wanted to make a good movie.

Josh Brolin was unable to eat whilst wearing his facial burn prosthetics.

Released on the same day with Toy Story 3 (2010). Director Jimmy Hayward is a former animator of Pixar, and worked on the first two Toy Story films.

Megan Fox's character Lilah refers to her mother as Mrs. Black, and says Lilah is short for Tallulah. Tallulah Black is a character who Jonah Hex helped get revenge on the man who raped and disfigured her. She eventually becomes a bounty hunter and on-again, off-again lover of Hex.

Composer John Powell was brought on to collaborate with the metal band Mastodon for the film. However, the film had to undergo reshoots and reedits, and Powell had other commitments, so he left and was replaced with Marco Beltrami, whose sensibilities were different and so Mastodon had to collaborate on a completely new score for the film, to their frustration.

John Malkovich wears a prosthetic nose in the film.

Thomas Jane showed interest in playing the role of Jonah Hex to the point of having himself photographed in costume complete with special make-up to recreate the character's massive facial scarring. Jane would later lend his voice for the character in an animated short film, DC Showcase Original Shorts Collection (2010).

Will Arnett was very keen to appear in the film, mainly because he so rarely gets offered straight dramatic roles.

Megan Fox's corsets were tightened up to accentuate her 20 inch waist (This was prior to Fox giving birth to her son Noah).

Megan Fox initially turned down the role of Lilah because in the script incarnation she read, she found it to be too violent and misogynistic. She changed her mind when Josh Brolin came on board and the script was re-written.

Matthew McConaughey and Emile Hirsch were considered for the role of Jonah Hex.

Jimmy Hayward reportedly did an uncredited re-write of the screenplay.

Due to the film's disastrous domestic box-office performance, the number of countries, in which it was due to be released internationally, was cut back.

Megan Fox's last scene was shot 48 hours before the cast and crew attended San Diego Comic Con in 2009.

Aidan Quinn shot his scenes in three days.

In July 2007, Mark Neveldine and Bryan Taylor were in charge of directing, and had adapted the screenplay too. In November 2008, however, they stepped down from being directors due to creative differences with the studio.

Megan Fox considers this to be her worst movie.

The sixteenth film released in select D-BOX enabled cinemas, located in the United States and Canada. In D-BOX's words, the motion control technology "adds to the movie's plot and underlying themes of fear, terror and explosive action by offering realistic sensations during most of the film's action scenes."

Francis Lawrence was ushered in late in production to do some reshoots.

Andy Fickman and McG were considered to direct the film.

This is the first comic-book film for Josh Brolin (Thanos in the Marvel Cinematic Universe films), Michael Shannon (General Zod in Man of Steel (2013)), Megan Fox and Will Arnett (April O'Neil and Vernon Fenwick in Teenage Mutant Ninja Turtles (2014)).

Jimmy Hayward wore a stylized cowboy hat throughout filming.

This film combines three members from Michael Bay's Transformers films: Mitchell Amundsen had worked on the first film, Megan Fox worked on the first and second film and John Malkovich had worked on the third film.

Brent Hinds: Vocalist and guitarist for progressive metal band Mastodon, makes a cameo appearance during the scene where the train carrying U.S. soldiers comes under attack. Hinds is wearing a U.S. Army uniform and can be seen among the other soldiers. Mastodon, recruited by the film's director Jimmy Hayward, wrote the soundtrack for Jonah Hex.

Andy Ryan, Mitchell Amundsen: Ryan is the Stunk Crick barber, and Amundsen is the customer he's shaving.