 According to Brandos friend, Carlo Fiore, and his reminiscences in  his book "Bud: The Brando I Knew", it was Fiore who helped make some  key decisions about the famous taxi cab scene. It wasnt working to  Brandos satisfaction, and the actor was becoming increasingly  frustrated at being unable to find the truth about the scene. Fiore  told him that having a gun pulled on him by his brother would hit a  bullshit note with Terry, and that shocked disbelief that his  brother would do such a thing would be the most appropriate  response. Brando then went into a stormy conference with Kazan and  Spiegel before nailing the scene. Afterwards Kazan drew Fiore aside  and said "Next time you get an idea about a scene, bring it to me,  not Marlon, okay?" There is some doubt about the veracity of this  story however as one look at the original script reveals that  shocked surprise was Terrys reaction all along.