Just prior to Tom hagen's abduction by Sollozzo, he has a conversation with Johnny Fontane in which Johhny expresses his appreciation for Vito getting him the part in the Woltz film.

Johnny talks about the Christmas present he plans to get for his Godfather. Puzo writes:

He was sending the Don a present for Christmas that would knock his eyes out.....(Hagen's) interest was aroused. "What is it?" he asked. Johnny Fontane chuckled and said, "I can't tell, that's the best part of a Christmas present."

This is never mentioned again. I wonder what Johnny had in mind.