13. Mayoral meeting
The film’s director met with the mayor of Salzburg prior to filming to feel him out on how he felt his citizens would respond to the presence of Nazi Stormtroopers and flags on the streets, just 25 years after the real thing took place.
This is what Captain von Trapp thinks.
14. 21 going on 22
The actress who played Liesl (Charmian Carr) was actually 21, and not 16 going on 17 as her popular song may lead one to believe when the movie was filmed.
15. Kid stuff
The producers took a considerable license when it came to the family offspring. All the names and ages of the von Trapp children were changed in the film version. And the real von Trapps had an oldest son, not an oldest daughter. Indeed, Liesl’s character was utter fiction.
16. Special cameo
Ever so briefly, the real Maria von Trapp, her daughter, and granddaughter appear in the background of the “I Have Confidence” scene, which sees Maria leaving the convent for the von Trapp home.
17. A visit from Hitler
After the real Von Trapps fled Austria, their home was occupied by Heinrich Himmler. Adolf Hitler was said to have visited his right-hand man there many times.
18. Growing concerns
Because the actress who played the von Trapp’s youngest child, Gretl (Kym Karath) gained so much weight over the course of the filming, Plummer declared her too heavy to hoist onto his shoulders for the culminating mountain-climbing scene. As such, a lighter stunt double appears in that shot.