Although David Ogden Stiers plays the French horn very badly in this episode, he was an expert horn player in real life (making the annoyance of his bad horn playing an inside joke as well as an obvious running gag through this episode).
The tune Charles plays at the beginning of the episode is an out of tune version of "Suicide is Painless," the M*A*S*H theme song.
The music that Winchester plays badly on the French Horn is a theme heard in "Ein Heldenleben" and "Don Juan," both by Richard Strauss.
In addition to appearing as the theme, Suicide is Painless is also played (intentionally poorly) on the French horn by Major Winchester in an episode that involves a patient trying to commit suicide.
The title is based on the musical "The Sound of Music" by Richard Rodgers and Oscar Hammerstein II, who adapted the story of Maria von Trapp and the Trapp Family Singers. The original Broadway production of "The Sound of Music" opened at the Lunt-Fontanne Theatre on November 16, 1959, ran for 1443 performances and won (in a tie) the 1960 Tony Award for the Best Musical.