Another good one: When Fredo and Michael are having their drink in Havana, Michael tells Fredo that he's going to be assassinated after the Presidential New Year's Eve party. "Who?" Fredo asks. Michael replies, "Roth." But he draws out "Roth" and looks thoroughly disgusted when he says it. I inferred from his expression that he may have been disgusted with himself for having been taken in by Roth for so long before he finally figured out Roth's bad intentions.