The encounter between Moe and Michael is one of those genius scenes of script writing and filming; subtle in some ways and blunt in others.
Plus, it's that rarest of film occasions: an excellent performance by Alex Rocco.
Excellent point, dt, about Moe being in a precarious position because he has to let Barzini wet his beak. You have to wonder: did he think that the Corleones' giving him a big chunk of money to finish his hotel would be the end of their interest in it?
