Hal Hamilton exclaimed, "We had the star, we had the drivers. We had an incredible array of technical support, we had everything. Except a script", while Haig Alltounian, Steve McQueen's chief mechanic, recalled "We were winging it".
There is no audible dialogue from any of the characters for the first 37 minutes of the movie.
Steve McQueen had asked John Sturges to direct, but the two men couldn't agree on how to construct the movie. Sturges had already directed McQueen in The Magnificent Seven (1960) and The Great Escape (1963), and had wanted to make a film with a more conventional script that focused on the relationships of the racers and concluded in typical Hollywood fashion with an upbeat ending. McQueen was more interested in making a racing documentary and he insisted on using very little dialogue in the film, making the cars the stars of the picture. He also expressed a desire to emulate some of the art house dramas being released in Europe at the time and told Motor Trend magazine that he had been inspired by French director Claude Lelouch's award-winning film A Man and a Woman (1966). Sturges' traditional approach to the material would lead to a giant rift in the production as well as signal the end of his working relationship with McQueen and he left the movie before filming began. As he left, Sturges cited, "I am too old and rich to put up with this shit".
Film driver David Piper lost his leg because of a deep cut caused during a crash. Brake fluid and other debris got into the cut, which caused an infection and the need to amputate the leg. He received a special thanks "for his sacrifice" at the end credits.
Although the film was Steve McQueen's dream coming true, it left him with bitter feelings. There was the conflict with original director John Sturges, budget excesses, and even a strike by the entire crew.