Barbra asks about a film with the song "Blue Moon" in it.  One that
comes to mind immediately is "An American Werewolf in London (1981,
directed by John Landis), in which all the music used has some
reference to the moon.
 Also, it's not a film, but there was a memorable "Moonlighting"
episode where Cybill Shepherd sings "Blue Moon."
 Hope this helps.