 Executive producer and co @-@ writer George Lucas decided to make the film a prequel as he did not want the Nazis to be the villains again . After three rejected plot devices , Lucas wrote a film treatment that resembled the film 's final storyline . Lawrence Kasdan , Lucas 's collaborator on Raiders , turned down the offer to write the script , and Willard Huyck and Gloria Katz were hired as his replacements , with the screenplay partly based upon the 1939 film Gunga Din . 
