The Mob? More like Capitalism
Since Coppola did not want to encourage any negative stereotypes on Italian-Americans, he wanted to use an allegory of American capitalism instead. There are tons of capitalist themes in the film!
Italian Slang?
Coppola took on the script after Puzo finished it up. He wasn't Italian and didn't actually know the language, and Coppola immediately noticed. He saw that there was a lot of made-up Italian slang that Coppola did not like.