I wonder if Lucille Ball was approached to be in it?
It seems to me that Lucy was one of THE top comedians at the time who was not in the film.
I know that the filming was done during the summer months to better accomodate the schedules of all of the television stars who were in the movie, so it likely wouldn't have interfered with any of Lucy's T.V. work.
Maybe she wanted too much money? Maybe they never asked her at all? I think that she would have been great in the Ethel Merman part. If she just wanted a small part, like Jack Benny had, a quick cameo, that would have been fun, too.