Burt Reynolds broke his coccyx (tailbone) while going down the rapids when the canoe capsized. Originally, a cloth dummy was used, but it looked too fake - like a dummy going over a waterfall. While Reynolds recovered, he asked, "How did it look?". Director John Boorman replied, "Like a dummy going over a waterfall."
Billy Redden didn't know how to play banjo. To simulate realistic chord playing during "Duelling Banjos," another boy, a skilled banjo player, played the chords with his arm reaching around Redden's side while Redden picked. Musicians Eric Weissberg and Steve Mandel play on the soundtrack.
While filming the white water canoeing scene, Ned Beatty was thrown overboard and was sucked under by a whirlpool. A production assistant dove in to save him, but he didn't surface for thirty seconds. John Boorman asked Beatty "How did you feel?", and Beatty responded "I thought I was going to drown, and the first thought was, how will John finish the film without me? And my second thought was, I bet the bastard will find a way!"
According to Turner Classic Movies, John Boorman wanted Lee Marvin and Marlon Brando to play Ed and Lewis, respectively. After reading the script, Marvin said he and Brando were too old, and suggested that Boorman use younger actors instead. Boorman agreed, and cast Jon Voight and Burt Reynolds.
John Boorman wanted Vilmos Zsigmond as director of photography because he'd famously filmed the 1956 Soviet invasion of Hungary. Boorman reckoned that anyone who had filmed under the threat of Russian tanks and guns would be ideally suited to an intensive and grueling shoot, which Deliverance (1972) promised to be.
Billy Redden, the boy with the banjo, liked Ronny Cox and hated Ned Beatty. At the end of the dueling banjos scene, the script called for Billy to harden his expression towards Cox's character, but Billy couldn't pretend to hate Cox. To solve the problem, they got Beatty to step towards Billy at the close of the shot. As Beatty approached, Billy hardened his expression and looked away.
When John Boorman was looking for an actor to play the toothless hillbilly, Burt Reynolds suggested Herbert 'Cowboy' Coward, who had no front teeth, was illiterate, and stuttered. Reynolds had previously worked with Coward in a Wild West show in Maggie Valley, NC.
The cliff climbing scene was shot during the day, and underexposed with a bluish tint added in post-production. "Day for night" shooting was common until the late 1970s because of slow film stocks and anamorphic lenses that didn't let in as much light as spherical lenses, requiring a lot of lights.
When John Boorman first tapped Jon Voight to appear in the film, the actor was at a low point. His previous film, The All-American Boy (1973), was deemed an unsalvageable mess. Convinced his career was over, Voight credited Boorman with saving his life, then spending the next few months trying to kill him with extreme stunts during filming.
Jack Nicholson had agreed to play Ed as long as Marlon Brando played Lewis. However, the actors' combined fees added up to more than $1 million, half the movie's budget, forcing director John Boorman to cast cheaper actors.
Following the film, tourism increased to Rabun County by the tens of thousands. By 2012, tourism was the largest source of revenue in the county. Jon Voight's stunt double for this film, Claude Terry, later purchased equipment used in the movie from Warner Brothers. He founded what is now the oldest whitewater rafting adventure company on the Chattooga River, Southeastern Expeditions. By 2012 rafting had developed as a $20 million industry in the region.
Regarding the courage of the four main actors in the movie doing their own stunts without insurance protection, James Dickey was quoted as saying all of them "had more guts than a burglar". In a nod to their stunt-performing audacity, early in the movie Lewis says, "Insurance? I've never been insured in my life. I don't believe in insurance. There's no risk."
John Boorman's gold record for the "Dueling Banjos" hit single was later stolen from his home by Dublin gangster Martin Cahill. Boorman later depicted the crime in his 1998 film about Cahill, The General (1998).
The movie was shot primarily on the Chattooga River, which divides South Carolina and Georgia. Additional scenes were shot on the Tallulah Gorge in Georgia, Salem, South Carolina, and Sylva, North Carolina. Shots of the town which did not call for the actors to be present were shot in Monaca, Pennsylvania.
During the filming of the canoe scene, author James Dickey showed up inebriated and got into a bitter argument with John Boorman, who had rewritten Dickey's script. They had a brief fistfight in which Boorman's nose was broken and four of his teeth shattered. Dickey was thrown off the set, but no charges were filed against him. The two reconciled and became good friends, and Boorman gave Dickey a cameo role as the sheriff at the end of the film.
Don Wayne Reno and Arthur Smith are credited with the first recording of "Dueling Banjos" (also known as "Feudin' Banjos" and "The Battle Of The Banjos"). Prior to "Deliverance" both parts were played with banjos, at the same speed all the way through. Almost all modern bluegrass bands play the "Deliverance" version in the key of G. In the movie both the guitarist and banjo players play it in the key of A.
Though 'Dueling Banjos' won a Grammy Award for Best Original Song, it was in fact written back in 1955 by 'Arthur Smith' (XII) and had previously been used in an October 1963 episode of 'The Andy Griffith Show' .
The canoes used in the film are displayed at the Burt Reynolds Museum, located at 100 North U.S. Highway 1, in Jupiter, Florida. One of the canoes used (and signed by Ronny Cox) is on display in the Tallulah Falls Railroad Museum, Dillard, Georgia.
Emory University Chemistry professor Claude Terry consulted on the canoe trip and navigating the Chatooga and other rivers. After the movie's release, Claude founded Southeastern Expeditions, which provided raft trips with trained guides on whitewater rivers. Rafting the Chatooga, the Ocoee River in Tennessee, and other whitewater rivers has become very popular, especially in the summer. Claude is now retired.
No credit was given for the film score. The film has a number of sparse, brooding passages of music scattered throughout, including several played on a synthesizer. Some prints of the movie omit much of this extra music.
The rape scene as originally scripted, consisted mainly of swearing. The "squeal like a pig" phrase was an attempt to "clean up" the scene for later television broadcast viewing. John Boorman liked the "cleaner" version better and instead used it in the film.
An alternate ending was shot, but cut from the final version. It takes place a few weeks, perhaps months, after the main events. It appears in author/screenwriter James Dickey's original script as part of the final dream sequence, but not as the story's literal conclusion. Lewis walks with a crutch (in Dickey's screenplay, his leg is amputated below the knee). Ed, Lewis, and Bobby meet with Sheriff Bullard near the dam in Aintry. The sheriff directs them to a body on a stretcher, then uncovers it so they can look at its face. No identifiable details of the body are shown, a deliberate choice to make the audience uncertain whether the dead man is Drew, Don Job, or the Toothless Man. The body was played by Christopher Dickey, James Dickey's son, who writes about the scene in his memoir, "Summer of Deliverance", and even he doesn't know whose body it was supposed to be. In the screenplay, Ed awakens from the dream, terrified, just before the corpse's face is revealed.
The infamous "squeal like a pig" rape scene was somewhat improvised. The novel and original screenplay detailed the rape with no porcine lines. Ned Beatty later claimed credit for the pig idea. However, Christopher Dickey, son of author James Dickey, stated in his book "Summer of Deliverance" that a crewman suggested the line.
The original UK cinema version suffered minor BBFC censor cuts to secure an X certificate which includes the removal of two lines of dialogue said by the toothless man when threatening Ed after the rape scene, "He got a real pretty mouth, ain't he?" and "You got to do some praying for me boy, you better pray real good." And the death of the Mountain man where he is seen struggling with the arrow through his chest was reduced. All later home UK video releases are uncut with an 18 certificate.