At the end of Part II you see a close-up of a much older looking Michael. Some have suggested that he somehow aged significantly within a year due to his diabetes, which is ofcourse not the case. The reason why we see a much older Michael is because this was originally part of a scene when he would meet up with an 18 year old Anthony. The proof of this is provided by the latest draft of the screenplay. When FFC finished filming of Part II, he had shot 7 hours of film, so a great deal of scenes were left out in order to reduce the lenght of the film. Some of those scenes were restored in The Godfather Saga. But there's still hours of film that has never been shown before.

Maybe one day it will be recovered and restored as a mini-serie. That would be something.