Loosely based on the life of Henry Hill, the same man who was the basis of Goodfellas (1990), after he went into witness protection program. The films' respective writers, Nicholas Pileggi and Nora Ephron, are husband and wife.
(Possibly deliberate errors by film makers): The FBI would not send Vinnie to live in a town/city where there are other mobsters in the Witness Protection Program. Vinnie's reunion and subsequent crime spree with his old pals would be the very reason why they would avoid placing in a city with other mobsters.
After Vinnie marries Shaldeen in Reno, he is talking on the phone with Barney - and then puts Shaldeen on the phone to speak with Barney. When they're done, Barney asks Shaldeen to put "Vinnie" back on the phone. Shaldeen knows him as "Todd" not "Vinnie."
Barney: The Padres play the Mets every so often, though you folks would probably be Yankees fans. It's been my experience that most organized crime people are.