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.
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."
At the end of an early dialog between Sarah and her handmaid, Hagar stands up and turns around heading for the door. That's when we see that the back of her tight dress is held together with a modern-day zipper.
Narrator: [Tower of Babel story]
And the Lord said, "Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do."