Four other children were brought in to augment the singing of the seven von Trapp children - to produce a better, fuller, more polished sound. Among the four "extra singers" was the younger sister of Charmian Carr (Liesl), Darleen Carr.
In 1962, Julie Andrews and Carol Burnett appeared in a special, Julie and Carol at Carnegie Hall, and at the time, "The Sound of Music" was still running on Broadway. Ironically, in a sketch on this TV special, Julie and Carol did a spoof of the "The Sound of Music" in much the same way Burnett later spoofed movies on her own variety show The Carol Burnett Show. At the time, Julie Andrews had no idea she would later star in the film version.
In 2007, the American Film Institute ranked this as the #40 Greatest Movie of All Time.
In Austria the film is know as "Meine Lieder - meine Träume" ("My Songs - my dreams"). It's not very well known there though, and the ending of the film was cut when it hit Austrian cinemas in the 60s.
In real life, Georg Von Trapp was not stern. The Von Trapp children were upset and disturbed by the portrayal of their father in the film. 'Maria Von Trapp' requested that director Robert Wise soften the character of her husband, but Wise refused.
In the capacity of producer and director, Robert Wise won two statuettes but was unavailable to claim them due to his location shoot in Hong Kong on The Sand Pebbles.
In the closing shot, when the family is climbing over the hills to safety, it is not really Kym Karath as Gretl on the shoulders of Captain von Trapp. In the DVD version, it is revealed that while in Austria, Kym Karath gained a lot of weight. This was one of the last shots filmed and so she was evidently a bit too heavy to be carried on Christopher Plummer's back. Plummer requested a stunt double and that is who's seen being carried on his back.
In the original play the Captain and Baroness separate due to ideological differences: the Baroness refuses to stand up against the Nazis, and the Captain refuses to compromise with the Nazis.
Julie Andrews sang "Supercalifragilisticexpialidocious" to the children in the cast to entertain them between shooting. Since Mary Poppins hadn't yet been released, they just thought she'd made up the song for them.
Maria never uses the Captain's first name, "Georg", in the film. Instead, she calls him Captain, Sir and Darling.
One of only 4 productions to win both the Best Musical (or Best Play, as applicable) Tony (1960) and the Best Picture Oscar (1965). The other 3 are My Fair Lady (1957/1964), A Man For All Seasons (1962/1966) and Amadeus (1981/1984).
Originally to be directed by William Wyler, who actually scouted locations and toyed with the script. He had a different film in mind; tanks crashing through walls, etc.
Prior to 14 March 1938 Austria drove on the left-hand side of the road. This is why cars registered in Austria up until the Anschluss had right-hand drive.
Right after her talk with Maria, the Baroness is at the party talking to Max. The song the orchestra is playing is a song from the play version that was not used in the movie called "How Can Love Survive". This song was sung by the Baroness and Max. However, the tempo and rhythm of the song were altered quite dramatically, when played as a piece of orchestral music at the party in the film, hence the melody isn't immediately recognisable. The melody was stripped of the dramatic intensity and urgency that characterised it in the stage version, and was made to sound like a schmaltzy waltz.
Six burly Austrians were hired to pull the heavy car by two ropes while the actors push from behind when the von Trapps are escaping their home in Salzburg.
The actors had to be continually hosed down while filming the scene after they had fallen out of the boat, in order to remain dripping wet.
The costume that Duane Chase (Kurt) wears at the party is called a Tracht, an authentic Austrian costume. The jacket he wears is called a Loden.
The first musical number in the film, The Sound of Music, was the final sequence shot in Europe before the cast and crew returned to Los Angeles. It was filmed in late June and early July of 1964. Despite the warm and sunny appearance, Julie Andrews notes that she was freezing running up that mountain over and over again. Director Robert Wise has said that he had to climb one of the trees nearby to be able to overview the helicopter shoot without getting in the picture.
The first scene filmed was the scene in Maria's bedroom where Frau Schmidt brings the dress material, and later Liesl sneaks in through the window. One of the last scenes filmed was the "You are Sixteen" number, which appears in the film right before the scene in Maria's room. The two scenes were shot about 4 months apart.
The front and back of the Von Trapp estate were filmed at 2 different locations in Salzburg, Austria.