RUMOR: Sergio Leone, the director of this film, was once considered...

...to direct The Godfather (1972).

Source: Wiki: https://en.wikipedia.org/wiki/Sergio_Leone#1980s

Leone turned down the opportunity to direct The Godfather, in favor of working on another gangster story he had conceived earlier. He devoted ten years to this project, based on the novel The Hoods by former mobster Harry Grey, which focused on a quartet of New York City Jewish gangsters of the 1920s and 1930s who had been friends since childhood. The four-hour finished film, Once Upon a Time in America (1984), featured Robert De Niro and James Woods. It was a meditation on another aspect of popular American mythology, the role of greed and violence and their uneasy coexistence with the meaning of ethnicity and friendship. Feeling the final cut was too long, Warner Bros. recut it drastically for the American market, abandoning its flashback structure for a linear narrative. Lasting just over two hours, the recut version shown in North America received much criticism and flopped. The original version, released in the rest of the world, achieved somewhat better box office returns and a mixed critical response. When the original version of the film was released on home video in the US, it finally gained major critical acclaim, with some critics hailing the film as a masterpiece.

According to biographer Sir Christopher Frayling, Leone was deeply hurt by the studio-imposed editing and poor commercial reception of Once Upon a Time in America in North America. It would be his last film.