One of the first mainstream American films to feature male and female nudity (albeit artfully filmed in a light-and-shadow style) in the Garden of Eden sequences. Reportedly, neither Michael Parks nor Ulla Bergryd used body doubles for these scenes.
Franco Nero was dubbed by an uncredited actor in this film. It is possible, though, not confirmed, that several of the other Italian actors were dubbed as well, although the actors themselves can be seen mouthing the words.
French director Robert Bresson was hired in 1964 by producer Dino De Laurentiis as director. When he shot his first scene - the deluge - he requested the use of all the animals in Rome city zoo. The producers complied, but upon checking the daily rushes saw that the only thing Bresson filmed was the tracks of the animals upon a sandy beach. They were furious and Bresson was fired, John Huston took over the project, delaying production a further six months.
It was John Huston's original idea to have Charles Chaplin play Noah. However, Chaplin didn't much like the idea of appearing in a picture directed by someone else, and Huston wound up playing the role himself. Similarly, Huston wanted Igor Stravinsky to score the film. For unspecified reasons, this was never done, either.
In some cities (such as Atlanta, GA) this film, which was shot in Dimension 150, a "curved screen" process, was not shown on a curved screen during its first run, despite the fact that there existed Cinerama theaters in those cities. This did not happen with the second and last film released in Dimension 150, the much more successful Patton (1970).
As with many epics of the 1950s and 1960s Paul Francis Webster was called in to supply promotional lyrics to the main theme. The song was entitled "Song of the Bible" and Webster devised the following lyrics to fit Mayuzumi's opening theme music: "A long, long time ago / There was no earth, there was no sea / In all the endless dark, no star, no tree / And then it came to pass / Jehovah said "Let there be light" / And as the thunder rolled / He made the day and then the night."
When cast as Abel, Franco Nero could not speak or understand any English. Although his voice was dubbed by another American actor, John Huston helped Nero understand English by giving him audio recordings of William Shakespeare's plays to study.
In her memoirs, Ava Gardner wrote that she hated having to speak the stilted dialogue as it felt unnatural. Her director, John Huston, told her that she would speak them and make them sound convincing.
When Noah feeds the hippopotamus, he tells his wife not to be afraid as the animal will do her no harm, as it has no harm in it. This is not strictly true. Hippopotami are generally recognized as being the most dangerous animals in Africa due to their aggressive nature.