Burt Reynolds broke his coccyx while going down the rapids when the canoe capsizes. Originally, a cloth dummy was used, but it looked too much "like a dummy going over a waterfall". After Reynolds was injured and recuperating, he asked, "How did it look?" The director replied, "Like a dummy going over a waterfall."
Billy Redden, the boy with the banjo liked Ronny Cox, and disliked Ned Beatty. When at the end of the dueling banjos scene, the script called for Billy to harden his expression towards Drew Ballinger, Cox's character, he was unable to fake dislike for 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 - exactly as intended.
According to Turner Classic Movies, John Boorman wanted Lee Marvin and Marlon Brando to play Ed and Lewis, respectively. After reading the script, Marvin suggested that he and Brando were too old, and that Boorman should use younger actors instead. Boorman agreed, and cast Jon Voight and Burt Reynolds.
The rape scene as originally scripted mainly consisted of swearing. The "squeal like a pig" phrase came from a need to have the scene made more suitable for TV viewing. As it happened, John Boorman liked this "cleaner" version, and used it in the film.
When John Boorman first tapped Jon Voight to appear in the film, the actor was at a low point as his previous film The All-American Boy (1973) was deemed to be an unsalvageable mess. Convinced his career was over, Voight credited Boorman with saving his life. And then spending the next few months trying to kill him, due to the nature of all the extreme stunts in the film.
John Boorman was looking for an actor to play the toothless one of the pair of murderous hillbillies. Burt Reynolds suggested Herbert 'Cowboy' Coward, who had no front teeth, stuttered and was illiterate. Reynolds had worked with Coward in a Wild West show in Maggie Valley, NC.
John Boorman wanted Vilmos Zsigmond as his director of photography as he had 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 such an intensive and grueling shoot as Deliverance (1972) promised to be.
Ned Beatty was the only one of the four main actors to ever have paddled a canoe prior to shooting the movie, which is ironic since his character is the most inept and clumsy. The others learned on set.
This movie is in film history considered to be the "breakthrough" film of Burt Reynolds. By breakthrough, it marked his transition from acting and starring into super-stardom. This film reflects the start of the period of Reynolds enormous star power and box-office pulling power, his machismo persona being mixed with a critical recognized serious dramatic performance.
Unlike Ronny Cox with his guitar, actor Billy Redden did not know how to play banjo for the famous "Duelling Banjos" scene. To simulate the realistic chord playing on the banjo, another boy, who was a skilled banjo-player, played the chords with his arm reaching around at Redden's side while Redden picked. On the soundtrack, musicians Eric Weissberg and Steve Mandel are actually playing.
Jack Nicholson had agreed to play the part of Ed as long as his good friend Marlon Brando played Lewis. However, the combined fee of the two actors came to over $1 million, half the movie's budget, so director John Boorman was forced to go with cheaper actors.
The movie was shot primarily on the Chattooga River, dividing South Carolina and Georgia. Additional scenes were shot on the Tallulah Gorge in Georgia as well in Salem, South Carolina and Sylva, North Carolina. Monaca, Pennsylvania is represented in shots of the town which did not call for the actors to be present.
John Boorman had no real intention of using a second unit. As it transpired, one side of the river fell within the remit of the New York unit, the other belonged to the Chicago unit. This protracted state of affairs just confirmed to Boorman why it was pointless using a second unit.
Consulting on the canoe trip and navigating the Chatooga and other rivers was provided by a Emory University Chemistry professor, Claude Terry. After the movie was released , floating the Chatooga River, and rivers in Tennessee and Claude founded 'Southeastern Expeditions,' a company that 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 with amateur lovers of the outdoors, with many individuals making these trips during the summer. Claude Terry has since retired, and another operator provides these trips.
John Boorman's gold record for the "Dueling Banjos" hit single was later stolen from his home by the Dublin gangster Martin Cahill. Boorman later depicted this very same crime in his 1998 film about Cahill, The General (1998).
The cliff climbing scene was shot "day for night", meaning that the footage was shot during the day and underexposed with a bluish tint (in post-production). Because film stocks were so slow (up until the late 1970s), and the anamorphic lenses were slow (didn't let in as much light as spherical lenses), and a plethora of lights were often needed, day for night was common practice for many films with night scenes during that period of filmmaking. Faster film stock has made the technique less common.
Credited with the first recording of "Dueling Banjos" (its most common title, also known as "Feudin' Banjos" and "The Battle Of The Banjos") is Don Wayne Reno and Arthur Smith. Prior to "Deliverance" both parts were played with banjos, and it is 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 have capos on the second fret, denoting it is in the key of A.
The infamous scene in which Bobby (played by Ned Beatty) is raped and ordered to "squeal like a pig" by the hillbilly played by Bill McKinney was somewhat improvised. The novel and original screenplay detailed the rape with no porcine lines. Beatty later claimed credit for the pig idea, but Christopher Dickey, son of author James Dickey, stated in his book "Summer of Deliverance" that the line was suggested by a crewman.
An alternate ending was shot, but cut from the final version. This other ending apparently takes place a few weeks (or perhaps months) after the main events of the movie. 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. The scene shows Lewis, Burt Reynolds, walking with a crutch (in Dickey's screenplay, his leg is supposed to be amputated below the knee). The sequence depicts Ed, Jon Voight, Lewis and Bobby, Ned Beatty, meeting with Sheriff Bullard, James Dickey, near the dam in Aintry. The sheriff displays to them a body placed on a stretcher and uncovers it, so that they can look at its face. No identifiable details of the body are shown, which was a deliberate choice, to make the audience uncertain whether the dead man is Drew, Ronny Cox, Don Job, Bill McKinney, or the Toothless Man, Herbert 'Cowboy' Coward. 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 terrified from this dream, just before the face of the corpse is to be revealed.