 MGM vied for the rights to film "Show Boat" as early as 1938  (Universal Studios had owned the rights to the musical since 1929,  and had made their own film version of it in 1936). MGM had hopes of  starring the reigning operatic duo of Nelson Eddy (qv) and  Jeanette MacDonald (qv) in the roles of Gaylord and Magnolia. but  when that didnt happen, they showcased new stars Tony Martin and  Kathryn Grayson (qv) 