Well, Fredo wasn't the sharpest knife in the drawer. But, since you raised that interesting point, it just occurred to me that, maybe, Fredo was feigning ignorance of how to order a banana daquiri to make Michael think he hadn't been there before under any circumstances--which makes the Superman gaffe all the more impactful for Michael.
At the hotel Michael tells Fredo that the family is making an investment in Havana, and Fredo says thats great "Havana's my kind of town," indicating he had been there before. Then the subject comes up as to whether there is anyone Fredo kows in Havana, and Mike says Johnny Ola, to which Fredo says No I never met him. So the issue of Fredo's having been in Havana and the issue of Fredo knowing Ola are two different things.
BTW, TB you are correct about Havana being a hot tourist destination in the pre Castro days. It was not uncommon in the 50's for people to baord a plane in Miami, go to Havana for the night....do clubbing etc., and return at dawn the following morning.
