[1] After completing the tour with Vélez, Heindorf joined Warner Bros., composing, arranging and conducting music exclusively for the studio for nearly forty years.
He, along with George Stoll at Metro-Goldwyn-Mayer, were jazz aficionados well known in the black entertainment community for employing minority musicians in their studio music departments.
[3] Heindorf appeared on screen, uncredited, as the orchestra leader in several films such as My Wild Irish Rose (1947), Young Man with a Horn (1950), and I'll See You in My Dreams (1951).
He undertook the musical direction of Judy Garland's comeback film A Star is Born (1954) and made a cameo as himself in the premiere party sequence where Jack Carson's character congratulates him on a great score.
Census records from 1930 show that Heindorf was living at the time in the Hollywood Hills with his friend Arthur Lange, a bandleader and composer.