 During the scene where the heavies try to drown  Dustin Hoffman (qv) in the bathtub, Hoffman (always the method  actor) insisted upon being made to stay underwater as long as  possible to make it real. Several takes were done and Hoffman  insisted on being kept down longer in the water. By the end of the  scene, he had to be given oxygen. In his own words, "I said, Dont  press on my Adams apple, but try to really hold me under. Let me  see how long I can stay under. Let me see if I can fight you. Let me  see what happens."