Co-writer and director James Mangold said that Joaquin Phoenix and Reese Witherspoon developed a very codependent relationship during filming. According to him, after the filming wrapped, Phoenix admitted to him that he and Witherspoon had relied on each other so much that they made a secret pact. The deal was that if one of them left or dropped out, the other would leave as well.

When Johnny Cash wakes up on the tour bus, just after the Folsom Prison performance, he walks past guitarist Luther Perkins, who is passed out with a lit cigarette in his mouth, and puts the cigarette out. Perkins died a few months after the "At Folsom Prison" recording and performance. He fell asleep in his Tennessee house with a lit cigarette in his mouth, and died from injuries sustained in the resulting fire.

Joaquin Phoenix and Reese Witherspoon performed all of the songs themselves, without being dubbed. They also learned to play their instruments (guitar and auto-harp, respectively) from scratch.

During one scene, Johnny Cash is high and performing "I Got Stripes", he walks right up to June Carter and glares at her for an uncomfortably long period of time on-stage. According to co-writer and director James Mangold, this was unscripted and improvised by Phoenix and Witherspoon. Mangold said that he simply told Joaquin Phoenix to do what he would do in real life if he were angry at his girlfriend and then had to perform on stage with her. Much to Phoenix's surprise, this backfired and Reese Witherspoon responded to his actions by simply rolling her eyes, and continuing to perform the song. Phoenix later said that her reaction threw him off because his goal had been to make her as uncomfortable as possible on-stage.

The film was screened for the inmates of Folsom Prison, thirty-eight years after Johnny Cash's landmark performance.

Johnny Cash approved Joaquin Phoenix to play him in the film because he liked his performance in Gladiator (2000). June Carter Cash also approved Reese Witherspoon for her role in the film.

The scene in which Johnny Cash pulls the sink off the wall was not scripted; Joaquin Phoenix actually pulled it off the wall.

According to James Mangold, when Joaquin Phoenix was learning how to sing and play guitar like Johnny Cash, his voice was too high and the band learned how to play Cash's songs in a higher key. Just before filming started, Joaquin's voice dropped closer to John's level, and the band had to re-tune their instruments the original key.

Reese Witherspoon and Joaquin Phoenix were so nervous about having to sing that it caused tension in their relationship off-screen. Both admitted in interviews that they didn't get along and constantly argued during the six months of singing lessons prior to filming. It wasn't until filming started that they connected and became friends.

Waylon Payne originally auditioned for the role of Waylon Jennings. Co-writer and director James Mangold was so impressed by Payne's audition that he cast Payne as Jerry Lee Lewis. Interestingly enough, the actor who got the role of Waylon Jennings was Waylon's own son, Shooter Jennings.

June Carter Cash died before production began. Reese Witherspoon's research included looking through Carter's closet for inspiration.

When James Mangold asked Johnny Cash what his favorite film was, the singer replied Frankenstein (1931), "because it's about a man made up of all these bad parts and yet he still tries to do something decent and be someone decent."

In the 1956 Sun Records recording of "I Walk the Line," Johnny Cash flubs the final low note ("because you're MINE"). Joaquin Phoenix flubs the same note, in the same manner, in the film, as he sings "I Walk the Line."

The screenplay was sent to Joaquin Phoenix on a Friday. He called James Mangold on Monday morning, asking what he needed to do to play the part of Johnny Cash. Mangold told him to go out and buy a guitar, which Phoenix duly did the next day.

It took four years for the producers to secure the rights to the story from James Keach, who is a friend of Johnny Cash and his family. After Keach agreed, it took another four years to get the film made.

Kathy Cash, Johnny's second oldest daughter with his first wife, Vivian, walked out of a family screening of the film five times. She felt Phoenix and Witherspoon performances were "Oscar-worthy", but that her mother, Vivian, was cast in an unfair light. Also, she did not feel there were enough scenes of Johnny interacting with his children, and that the film portrayed her father too harshly. When her half-brother, John Carter Cash (an executive producer of the film) was asked about her reaction, he responded that the movie was intended to tell the love story between his mother and father.

Towards the end of the movie, Johnny tells his dad to tell the girls about the flood. This is a reference to a real incident in Johnny Cash's childhood when the family farm flooded that he wrote and sang about in his famous song "Five Feet High and Rising".

June Carter Cash's and Johnny Cash's only son John Carter Cash plays an uncredited character in the film, and served as an executive producer.

Joaquin Phoenix wears fifty-six different costumes. All were designed by Arianne Phillips following meticulous research within the Cash family's archives and fans' private collections.

Reese Witherspoon and Joaquin Phoenix had vocal training for six months with music producer T Bone Burnett.

Due to the similarities between his lifestyle and Johnny Cash's, Joaquin Phoenix was hospitalized after filming.

For the Folsom Prison sequence, Joaquin Phoenix insisted that the crew members playing the wardens didn't let the extras playing inmates eat, drink, or go to the toilet. This helped create a particularly tense atmosphere on set.

There was a consensus opinion that the only reason this movie got greenlit was because of the success of Ray (2004). The truth is that this film was well into production when Ray (2004) came out.

At 5' 8" tall, Joaquin Phoenix is six inches shorter than the 6'2" Johnny Cash.

Reese Witherspoon grew up in Nashville, Tennessee and was a huge fan of Dolly Parton growing up. In her Oscar acceptance speech, she thanks the film's music director and producer T Bone Burnett for "helping me realize my childhood dream of being a country music singer."

Johnny gets fan mail from a Folsom Prison inmate named Glen Sherley. In real life, Sherley was an inmate at Folsom when Johnny Cash recorded "At Folsom Prison". He also wrote "Greystone Chapel", which Johnny recorded during the show.

Tyler Hilton originally auditioned to play a background musician and extra. He played an Elvis song during his audition, and was subsequently cast as Presley.

The film owes its genesis to a 1993 episode of Dr. Quinn, Medicine Woman (1993). Johnny Cash was guest starring on the show and had become friends with the star, Jane Seymour, and her husband, director James Keach. Cash suggested to Keach that he should tackle a film of the singer's life which he readily agreed to, so Keach and Seymour started compiling interviews with Johnny Cash in preparation for a script. By 1997, Gill Dennis had enough material to put a screenplay together, but the project had stalled. That's when Keach reached out to James Mangold, knowing the director had been lobbying hard for the chance to get involved.

Despite what was depicted in the movie, Johnny Cash actually had a drug problem throughout his entire adult life, going only a few years in between without taking any drugs.

When Johnny Cash first approached the recording studio, a pair of young men are rhythmically polishing shoes, an homage to Johnny Cash's song "Get Rhythm", in which he sings about a shoeshine boy on the corner of the street.

Cinematographer Phedon Papamichael shot the concert scenes mainly with hand-held Super 35 cameras, as he didn't want to give a false sense of glamor to the performances.

James Mangold was looking to cast an actor who would come across as "an angry, sensual, tortured young man". He knew he'd found that actor when he watched Gladiator (2000).

Sony, Universal Pictures, Focus Features, Paramount Pictures, and Warner Brothers all passed on the project.

At the 2006 Oscars, Joaquin Phoenix was nominated alongside actor Heath Ledger for Actor in a Leading Role. Both men would later go on to play the Joker, and both men won Oscars for their portrayal of the character.

In the same year, Robert Patrick played Johnny Cash's dad in this film as well as Elvis Presley's dad in Elvis (2005).

After visiting many of Johnny Cash's old houses, production designer David J. Bomba created ninety different sets for the film and tried to underline the contrast between Cash's two lives, one that was close to earth and nature in Arkansas and Tennessee, and the other set in the fast-moving world of rock music.

When Johnny Cash is drunk walking in the rain and begins singing a song about June Carter, the song is the same rhythm of "Hey Porter", which was one of Johnny Cash's first hit singles.

When Cash calls his wife during his first show, a sign on the wall says "Ring in case of fire."

Although Johnny Cash often wore leather, all of his costumes for this film were made with synthetic leather instead of authentic leather in order to accommodate Joaquin Phoenix, who is a strict vegan.

Shelby Lynne grew up listening to Johnny Cash's music. She composed the song "Johnny Meet June" the day he died.

It's not generally known that one of Johnny Cash's signature songs - "Ring of Fire" - was actually written by his wife, June Carter Cash.

In the 2006 Oscars, Joaquin Phoenix, nominated for portraying a real-life celebrity, was in competition with two other actors who played a celebrity: David Strathairn (Edward R. Murrow in Good Night, and Good Luck. (2005)) and Philip Seymour Hoffman (Truman Capote in Capote (2005)). Hoffman won.

The only film that year to be nominated for Best Actor and Best Actress Oscars. Reese Witherspoon won the latter for her role, while Joaquin Phoenix lost to Phillip Seymour Hoffman for his role in Capote (2005).

Every day, before filming began, Joaquin Phoenix would walk up to James Mangold and tell him "Say that thing" and Mangold would reply with "You're not Johnny Cash". This made Phoenix happy as it alleviated him of the weight of expectations about playing such an icon.

Johnny Cash's daughter Rosanne Cash was not a fan of the film. "It was like having a root canal without anesthetic," she said.

Tyler Hilton, Waylon Payne, and Johnathan Rice are all singers in real life.

When The Tennessee Three play "Rock and Roll Ruby", a sign on the wall behind the audience says "CLASS OF 1955". This may be a reference to the group set up by Johnny Cash, Carl Perkins, Jerry Lee Lewis, and Roy Orbison, called "Class of '55".

When country singer George Hamilton IV first viewed the movie, it seemed to him like he was actually watching the young Johnny Cash (whom he knew) and not an actor.

Waylon Payne has a few personal connections to the characters in the film. Marshall Grant, bassist for The Tennessee Three, discovered Sammi Smith, Payne's mother. Waylon Jennings, Johnny Cash's friend and collaborator, was his godfather.

Elvis Presley's band members in the film were played by The Dempseys.

The first guitar that Johnny buys in the film during his stint in Germany is a Hoffner Congress. Although he gets it in 1952, the Congress wasn't actually introduced until a year later. His ability to afford it would've been in line with that particular model because, even brand new, it was a bottom-of-the-line product.

The biggest grossing musical biopic until Straight Outta Compton (2015).

While June Carter Cash was older than Johnny Cash, Reese Witherspoon is younger than Joaquin Phoenix.

Johnny's gig with his new trio in Texarkana was at the cities Municipal Auditorium in September of 1955. Although the film depicts Jerry Lee Lewis and Roy Orbison on the bill it was actually a Cash-Presley performance.

James Mangold was initially reluctant to consider Shelby Lynne in the part of Cash's mother as he only knew her from her album covers in which she always appeared quite glamorous. When he met her, however, he realized that Lynne had no interest in being glamorous and was actually a true country girl at heart, exactly what the role required.

Reese Witherspoon appears for the first time thirty minutes into the movie.

The only film that year to be nominated for Best Picture at the Producers Guild of America Awards, but not at The Academy Awards.

Roger Ebert was genuinely surprised to learn that it wasn't Johnny Cash's voice that he heard on the soundtrack but Joaquin Phoenix's.

Joaquin Phoenix had coincidentally met Johnny Cash six months before he first heard of a film being made about the singer.

Although his appearance in the film was very brief, Waylon Payne 's portrayal of Jerry Lee Lewis - particularly his nose-up, head-twirling hyper-egotistical body language - is the most accurate ever seen. Rockabilly legend Carl Perkins ("Blue Suede Shoes") once referred to Lewis by saying, "If you want to know who was the very best piano player who ever lived, just ask him."

Waylon Payne is teetotal in real life but, given as he was playing notable hard-living Jerry Lee Lewis, he felt obligated to return to drinking briefly to help him get into the spirit of his reckless character.

Reese Witherspoon dyed her hair brown after filming for Just Like Heaven was wrapped

Joaquin Phoenix and Robert Patrick appeared in Ladder 49 (2004).

The rooster character that young Johnny quotes in his joke about feathers getting blown off is Foghorn Leghorn, from one of his Warner Bros. cartoons. However, his cartoons didn't begin production until two years after the scene takes place.

It's worth remembering that in the same year that Johnny Cash and Jerry Lee Lewis first hit the big time, the number one record in the USA at the time was Patti Page's "How Much is That Doggie in the Window".

Gill Dennis, who co-wrote the screenplay, was actually James Mangold's teacher at film school.

The film has its origins in a 1993 episode of Dr. Quinn, Medicine Woman (1993).

James Mangold became a father just days after the film wrapped.

Brit Shaw's debut.

Two actors both starred in Disney movies. Ginnifer Goodwin starred in Zootopia and Joaquin Phoenix in Brother Bear.

Actresses Ginnifer Goodwin and Clare Grant both were born in the city of Memphis, TN where the film was partially filmed and partially set.

Ironically, the actress Ginnifer Goodwin, who plays Johnny's first wife Vivian, looks like Priscilla Presley, Dallas Roberts, who plays Sam Phillips, looks like Elvis's cousin Gene Smith, and Robert Patrick, who plays Johnny's father Ray, looks like Elvis's father Vernon Presley.

James Mangold and the film's producer Cathy Konrad were husband and wife at the time of filming. They divorced in 2014.

Kerris Dorsey's debut.

Second time Joaquin Phoenix had a character named Jack in his movie the first one was a year earlier in 2004 where he portrayed a firefighter named Jack Morrison with the Baltimore Fire Department in Ladder 49. this one the younger character he portrays when hes older had a brother named Jack sadly both do not live to the end of the film.

June Carter Cash is 3 years older than Johnny Cash. Reese Witherspoon is 2 years younger than Joaquin Phoenix.

Johnny Cash really did propose to June Carter Cash on-stage. It happened in February 1968, at the London Ice House, a hockey arena in London, Ontario, in the middle of a performance of "Jackson". She accepted, and they married a week later.