Trivia: The front and back of the von Trapp house are actually two different houses. Also, the gazebo (which belongs to the house used for the back shots) is across a river from the house. You can take the Sound of Music tour in Salzburg.
Trivia: Not a mistake, just a fact. Exactly 2,357 pies were used in the big pie fight.
Trivia: At many points in the movie, the music playing in the background are slightly different versions of the song "A Hard Day's Night." This was the title track from the Beatles previous movie.