When Al and Bettye fly to New York to screen the movie, they bring three 35mm film shipping containers. Each container holds two reels of 35mm, which each holds about 20 minutes of film. Three containers with a total of six reels holds about 120 minutes, or about two hours of film. However, The Godfather was 175 minutes long, which means they'd actually need five shipping cases to hold nine reels of film.
While in Sicily, Bruno is referred to as Cosa Nostra by the Italian AD and Al Ruddy. Cosa Nostra is an American Mafia term. It is Italian for "Our Thing", "This Thing of Ours". Sicilian Mafia would never use or be referred to by this term.
Lapidus' secretary uses the phrase "Will have to circle back to you" on the phone. This was not an expression in 1971.
When Ruddy visits Joe Columbo in hospital, the patient gown that Columbo is wearing is of a modern type, not like those used in hospitals in the early 1970s.