 John Milius contributed dialogue polishes, and "Sugarland Express" writers Matthew Robbins and Hal Barwood also made uncredited contributions.Spielberg has claimed that he prepared his own draft, although it is unclear to what degree the other screenwriters drew on his material.One specific alteration he called for in the story was to change the cause of the shark's death from extensive wounds to a scuba tank explosion, as he felt audiences would respond better to a "big rousing ending".