Erich Wolfgang Korngold, who supervised and arranged the music of Wagner for this, his final film assignment, also appears on screen as famous conductor Hans Richter. Korngold had to take the small role when the actor originally cast failed to show up. With over 1000 extras in full costume on set, director William Dieterle pleaded with Korngold to take the non-speaking part, to save the shoot.
Only the second Hollywood feature of British stage actor Alan Badel, which is presumably why, despite playing the main role of Richard Wagner, he gets fifth billing.