Richard Harris desperately sought the lead role, despite being repeatedly refused due to his limited singing ability. At one point he even paid a man to carry a board down the Strand that said, "Harris Better than Burton, Only Harris for Camelot". When Vanessa Redgrave was cast as Guenivere, Harris sent a note to producer Jack L. Warner, which read, "Height of Vanessa Redgrave: 5 feet 11 inches. Richard Burton: 5 feet 10 inches. Richard Harris: 6 feet 2 inch." According to his salute for kirk Douglas at AFI ceremony
At one point, while filming on a Warner Bros. soundstage, Richard Harris and producer Jack L. Warner were at odds over how to do a scene. Warner took Harris out onto the studio lot, and showed him the famous water tower with the Warner Bros. logo on it. "What does that tower say, Richard?" asked Warner. "It says 'Warner Brothers,'" Harris replied. "Right," said Warner. "Now when it says 'Harris Brothers,' *then* we'll do it *your* way."
Julie Andrews was asked to reprise her stage role of Guenevere, but had become such a popular film star by this time that she was unable to accept the role. Ironically, Jack L. Warner, who produced the movie version of Camelot (1967), was the same man who produced the film version of My Fair Lady (1964), and who had given the role of Eliza Dolittle to Audrey Hepburn because he thought that Julie Andrews would not be a big enough box-office name. Warner apologized to Andrews on his troubles about the My Fair Lady casting and the two became in good standing with each other from that moment forward. Andrews, ultimately, did not get to reprise her role, because the film's director Joshua Logan wanted Vanessa Redgrave for the role, instead.
In addition to actual Medieval castles in Spain used in this film, a castle was built on the back lot of Warner Brothers Studios for closer shots and direct storyline action. Long known at the studio as the "Camelot Castle" after filming ended, it was used in other films. In 1972, the Camelot Castle was renovated into a Tibetan Lamasery for the musical remake of Lost Horizon (1973), and it was used extensively in the TV series Kung Fu (1972). In the 1980's, the back lot castle was torn down to make room for an office building. Fortunately, the Alcazar de Segovia and the Coca Castle remain in Spain where they are both popular tourist attractions.
Two separate Medieval castles in Segovia, Spain, were used in this motion picture; one as Sir Lancelot's Castle in France and the other as Camelot itself in various long shots. The Alcazar de Segovia, with its mansard roofs and numerous turrets reminiscent of Disneyland's Sleeping Beauty's castle, was depicted as Sir Lancelot's home in Gaul (France)in this film. The opening and closing scenes were also filmed on the grounds of this same castle which may be seen in the background in the light of the approaching dawn. For Camelot itself, the Coca Castle, also in Segovia, was used in long shots and background shots to depict the towers and battlements of Arthur's legendary kingdom.
Richard Harris and David Hemmings became lifelong friends and Harris never forgot the time Hemmings talked him out of suicide. During one rocky period in the film's production, Hemmings had come to collect Harris from his house in the Hollywood Hills. When he arrived, he found Harris on a balcony above the swimming pool. "I'm going to jump", Harris announced. "You can't do that", Hemmings protested. "There's no water in the pool". Harris replied, "I don't give a fuck. I fucking hate Warner Brothers and fucking Hollywood, the people here are all fucking arseholes". Hemmings climbed out on to the balcony. "Are you sure you really want to do this?" Harris' face fell. "No, I don't. Let's have a drink".
Richard Burton, who had played the role of King Arthur on Broadway in the original 1960 production, was offered the role in the film. Burton had had a huge success with Lerner & Lowe's show, winning a 1961 Tony Award for Best Actor in a Musical, but he turned the film down; a decision he would regret later on. Burton subsequently played King Arthur in a 1980 touring revival of "Camelot", to make up for his prior decision, although he had to drop out in April 1981 due to ill health and was replaced by Richard Harris.
Vanessa Redgrave and Franco Nero who met on this film would later on in life get married and have a child together (Carlo Gabriel Nero). They have also worked together since in Letters to Juliet (2010) as lovers who found each other after years apart.
The song "If Ever I Would Leave You" won a Golden Globe Award for Best Original Song Written for a Motion Picture, even though it was not written especially for the film but for the original stage production of "Camelot", and all the other nominees were songs especially written for films. In addition Frederick Loewe won a Golden Globe for "Best Original Score", a score that he had actually written for the Broadway stage, not for films. This is the only instance in the history of the Golden Globe Awards that this has happened.
At a celebrity bash, David Hemmings began playfully sparring with his fellow guests. Richard Harris took offence to this and, demonstrating his own boxing prowess, landed a punch that split Hemmings' lip. Upon seeing this, Vanessa Redgrave burst into tears and announced that she'd never work with Harris again.
In addition to being used in the 1973 remake of "Lost Horizon", the Camelot Castle set was used in the 1972 TV movie of "The Hound Of The Baskervilles" (as Baskerville Hall) and as a Scottish ancestral home in a segment of the "Macmillan And Wife" TV series.
In the original musical, Merlin is lured away from Camelot by the spirit of Nimue, who sings the song "Follow Me." Nimue was dropped from the film, and the song is sung by a chorus during the last of the scenes with Merlin.
Because Warner Brothers was a dry studio, drinking buddies Richard Harris and David Hemmings smuggled in alcohol in a prop van and discarded the empty bottles in a couple of portaloos. One afternoon, Jack L. Warner was showing a group of distinguished Japanese tourists around the studio when one lady was suddenly caught short and rushed to Harris' portaloo and opened it, causing bottles to crash out. Harris grabbed the woman and ran off, leaving Hemmings alone with a suitably embarrassed Warner. When Harris returned, he ordered the crew to clean up the mess and as he let with his guests, he whispered out of the corner of his mouth to the two actors, "This bar is now closed".
When Richard Burton was considered to reprise his stage role as King Arthur, Warners considered casting Elizabeth Taylor as Guinevere and Peter O'Toole as Lancelot. This was scrapped for being potentially too expensive.
Richard Harris insisted on cutting Lancelot and Guinevere's love scene, because he felt that it reduced the dignified aspects of the king. When Jack L. Warner refused to comply, Harris burst into his office and started pounding on the desk.
Much like their characters, Vanessa Redgrave and Franco Nero were lovers at the time. Unfazed, Warner stood up, took Harris by the arm, led him towards the studio gates and pointed towards the sign above the entrance. He said, "What does that say?" Harris meekly replied, "Warner Brothers". Warner replied, "Right. And when it reads Harris Brothers, you can rewrite Camelot any way you want. But not till then".