When filmed?

The trivia section says this was shot in 1963, but there is a scene in the movie where a character talks about what he did in 1965. How could that have been shot in 1963? Was the picture shot piece-meal at different times when financing came in? Does anyone know when it was finally finished? I really love this film, but De Niro fanatics should stay away: he doesn't play the lead and even in a small part he is no more interesting than a lot of the actors.