Fred Zinnemann was another choice to direct; Sam Spiegel very much wanted him to take the job, due to his box-office clout, but Zinneman didn't understand the novel and declined. Orson Welles was reportedly approached to co-star and direct, but Welles, too, dropped out after reading the script. William Wyler was considered but never formally approached. Ultimately, Spiegel explained the decision to hire David Lean as being "In absence of anybody else."
Sessue Hayakawa edited his copy of the script to contain only his lines of dialog. This way, he remained oblivious to the real nature of his character's fate.
Sessue Hayakawa was 68 years old when he was cast as Saito. Having limited command of the English language, he focused only on those pages of the script in which he had dialog - the rest of the pages he tore out. The complete script was about one inch thick; Hayakawa's with the pages torn out was about an eighth of that.
Ian Watts, longtime professor of English at Stanford, and author of the landmark "The Rise of the Novel", was a prisoner in the camp, helped with the construction of the bridge, and served as an advisor during the making of the film.
After a successful stunt test for the film's climax, where a Japanese soldier falls off the bridge into the river, stuntman Frankie Howard was swept under the strong current during the actual shooting of the scene. Prop man Tommy Early dove in to save him but was also pulled under. Once they stopped struggling against the current, both men were carried to a point in the river where they were rescued. Unfortunately, Howard later died from a stomach illness while in the Hospital for Tropical Diseases back home in England.
After filming was completed on the exploding bridge sequence, which cost an enormous amount of money and time, rumor has it that the footage disappeared somewhere between Ceylon and London. It was finally discovered two weeks later, sitting in the intense heat out on the runway at the airport in Cairo, Egypt. Miraculously, the footage was undamaged.
After the bridge was blown, souvenir hunters swarmed all over the set, claiming pieces of timber.
After the final scene was shot, producer Sam Spiegel shipped the film footage on five different planes to minimize the risk of loss.
Although a major player in Hollywood, producer Sam Spiegel was based in London. Upon meeting Spiegel, David Lean was won over by the man's larger-than-life personality and charm. Their working relationship however would not always be harmonious.
Around the time that he was offered The Bridge on the River Kwai, David Lean had little money and was very much in need of a new project. He was contracted for $150,000 to be paid in installments. As soon as he signed, Lean borrowed $2000 from Columbia Pictures to get his teeth fixed.
Assistant director John Kerrison was killed in a car crash on the way to one of the locations. A make-up man was badly injured in the same accident.
At one point during filming, David Lean nearly drowned when he was swept away by a river current. Geoffrey Horne saved his life.
During shooting, Alec Guinness continued to have doubts about his performance and the direction he was getting from David Lean. To put Guinness at ease, Lean decided to show the actor a rough cut of certain sequences. One night, Lean ran over an hour's worth of footage for Guinness with the actor's wife and son also attending. During the screening, nothing was said. At the end, the Guinness family thanked Lean and promptly walked out, leaving the director without a clue as to what to think of their reaction (or lack of). Later that night, Lean received a visit from his lead actor who told him that he and his family had decided that Nicholson was the best thing that Guinness had ever done.
For one sunset scene, David Lean specifically traveled 150 miles to capture it.
For the scene when Colonel Nicholson emerges from the oven after several days confined there, Alec Guinness based his faltering walk on that of his son Matthew Guinness when he was recovering from polio. Guinness regarded this one tiny scene as some of the finest work he did throughout his entire career.
For the scenes where William Holden, Jack Hawkins, Geoffrey Horne and the native girls had to wade through swamps, they were wading through specially created ones. The real swamps in Ceylon were deemed to be too dangerous. Nevertheless, the leeches in the recreated swamps were real.
In order to save money, Sam Spiegel actively looked into making the film in Yugoslavia. Naturally, a European location simply couldn't match the jungle setting the film required.
In the scene where Colonel Nicholson ruminates on the completed bridge to Saito, actor and director argued over how the scene should be shot. Guinness wanted a close-up of his face, while Lean insisted on shooting him from behind. Nevertheless, Guinness loved his dialog and deliberately timed his delivery to coincide with the setting of the sun.