I just put a library hold on three Eddy-MacDonald movies: "Rose Marie," "Maytime," and "Phantom of the Opera."
Jeanette wasn't in Phantom. His co-star was a young ingenue named Susannah Foster (possibly still in her teens in 1942).
You'll find that it's very, very different from the Lloyd Webber musical, and very different from the original book. Claude Rains is very much the star.......except, of course, for that magnificent baritone Eddy voice. :o)
The underground set in it is the same one they used in the silent movie Lon Cheney version.