Another anomaly re. Fredo and Havana:

When Fredo asks Michael if there's anyone in Havana that he knows, Michael gives him the piercing look and says, "Oh, Hyman Roth, Johnny Ola..." Fredo replies: "No, I don't know those guys." Later, at the Yolanda show, when Ola shows up at their table, Michael, with another piercing look, says, "Johnny, I don't belive you know my brother Fredo." He says, "We never met."

At Anthony's party, when Michael introduces Ola to Tom, Ola says, "I remember Tom from the old days." Fredo was only a few years younger than Tom. If Tom and Ola knew each other from "the old days," so would Fredo. And, given the close association between Vito and Roth, Fredo would have known Roth, too. So, Michael should have known right away that Fredo was lying about not knowing Ola and Roth. Right then and there he should have figured out that Fredo was the traitor. But if he had, we'd have been spared the Superman show revelation and all the drama that followed...