What actors and actresses appeared in Showboat Serenade - 1944?

You're likely thinking of the 1946 film "Showboat", which was a musical adaptation of the classic Jerome Kern and Oscar Hammerstein II opera.

The cast of "Showboat" (1946) included:

* Kathryn Grayson as Magnolia Hawks

* Howard Keel as Gaylord Ravenal

* Ava Gardner as Julie LaVerne

* Joe E. Brown as Frank Schultz

* Angela Lansbury as Ellie May

* J. Edward Bromberg as Cap'n Andy Hawks

* William Warfield as Joe

* Robert Sterling as Steve Baker

* Gladys Cooper as Parthy Ann Hawks

* Lionel Stander as Pete

Please note that there is no record of a film titled "Showboat Serenade" from 1944.