The Cure from X Men The Last Stand: mentioned in Wolverine...
It would have been nice if they had mentioned 'The Cure' from X3 at some point, seeing as how this takes place after that.
Logan wanted mortality...or so that was the theme of the movie; the cure from X3 would have made him mortal.
There could have been a scene where Yashida mentions that he was worried that Logan might have taken the cure before he got a chance to extract his abilities, or something..i think the film makers missed a great opportunity here as the two films tie into each other nicely...
"And a man, a man provides. And he does it even when he's not appreciated, or respected, or even loved. He simply bears up and he does it. Because he's a man."
- Gus Fring