The music was played by pianist Carmen Cavallero in his own style. He had a completely different, and more technically precise, style of playing than Eddy Duchin had. If you listen to recordings by both this is clearly evident.
The characters of "Mr. and Mrs. Sherman Wadsworth" are fictionalized versions of the real-life Mr. and Mrs. W. Averall Harriman, Marjorie Duchin's uncle and aunt. Averell Harriman was the heir to his father's, George Herriman, railroad fortune, and devoted most of his life to public service, including stints as US ambassador to the Soviet Union and to the Paris Peace talks during the Vietnam War. At the time "The Eddy Duchin Story" was released (1956), Harriman was in the midst of his term (1955-1959) as Governor of New York, and was a candidate for the Democratic presidential nomination that year.
Duchin's first wife was Marjorie Oelrichs, a cousin of Blanche Oelrichs, the wife of John Barrymore. As a young man living in New York, Tyrone Power was very close to the Barrymore family and was required by Blanche to be at her weekly salon gatherings.
Andrew Paul Smith, who played the young clarinetist and Peter's friend, mimed his playing. George W. Smith, who was the actual player and Andrew Paul Smith's father, was first chair clarinet in the Columbia Studios Orchestra. Andrew Paul Smith had no further involvement in the motion picture or television industry in any form after appearing in The Eddie Duchin Story. (information supplied by Michael W. Smith, brother of Andrew)