According to Dreyfuss, he and Shaw started a friendly relationship before they shot their scenes together... but on set, "he was possessed by some evil troll that would make me his victim. " The late Roy Scheider, who played Brody, posited that Shaw was bothered by Dreyfuss' inexperienced haughtiness and decided to put the young actor in his place. Shaw's habitual drinking didn't help calm his temper, either...
Shaw notoriously taunted Dreyfuss for his weight and goaded him by daring him to perform daunting acts. In one instance, Shaw tried to convince Dreyfuss to climb to the mast of the boat and jump off. In addition, Shaw also mentally tampered with his rival right before the cameras started rolling, telling him to, "mind your mannerisms". Dreyfuss finally reached his boiling point when Shaw asked for help while he was walking down the boat's gangplank, bourbon in hand. In retaliation, Dreyfuss swatted the glass away while the crew held their breaths, and shot his next scene with Shaw pointing a fire hose at his face.