I'm rereading the novel and I came across a few things that are curious.

Michale wakes up with Kay about 10PM and then sets out for the hospital. He discovers Vito alone, then with the nurse moves Vito to another room. He then takes up a position in front of the hospital when along comes Enzo to visit Vito. It had to be upwards of 11PM by then. Why would Enzo think that was a proper time to visit Vito? Then when the cops arrive, Vito takes off. Yet later Sonny (or Tom maybe) says that Enzo told them that he stuck with Mike when Sollozzo's hitment drove by. When would he have told them that?