I believe that in a recent Harp Column (or was it the American Harp Journal?) interview with Robert Maxwell, he said he did record the Hungarian Rhapsody for Harpo in “A Night in Casablanca” because Harpo wanted to play it but it was too complex for the time he had to learn it. Otherwise I believe Harpo played most of what you hear in his movies. I had always wondered why that particular movie solo sounded almost identical to Maxwell’s version on one of his early records. That interview answered the question.
Regarding an earlier post where Spring Byington plays a pedal harp, that’s a movie called “My Love Came Back,” starring Olivia de Haviland, where Spring is the wife in a musical family. It’s easy to confuse with the Judy Garland movie (“In the Good Old Summertime”) because Spring Byington is in both movies, as is S.Z. Sakall. In the latter film, Garland plays a folk harp, although not convincingly. The song is (Meet Me Tonight in) Dreamland. Incidentally, Robert Maxwell made a nice recording of that, too. Sure wish more of his recordings were available on CD.