In the hours before shooting, Robert cast the final members of the most popular family in cinematic history: Charmian Carr as Liesl; Nicholas Hammond as Friedrich; Heather Menzies-Urich as Louisa; Duane Chase as Kurt; Angela Cartwright as Brigitta; Debbie Turner as Marta; and Kym Karath as youngest daughter, Gretl.
Forty-five years later, some of the actors have families of their own and say they love watching the film with their children. "I think this movie is the world's best babysitter," Nicholas says. "Everybody I know has parked the kids in front of it. Three hours of dead silence."