Wise’s The Sound of Music picnic is among film’s happiest and most exuberant picnics. It’s his creation because Rodgers and Hammerstein’s musical does not have picnic. Maria and the children sing “Do-Re-Mi” while marching in the Trapp residence.
The filmed episode begins with a romp through Salzburg as
Maria and the children collect items for their picnic from the open-air markets. Running along a path to the river Salzach, they board a tram, at last, reaching a grassy meadow ringed with alps where they settle. 
When one of the little ones ( I can’t tell who) asks: “Fräulein Maria? Can we do this every day?” Maria replies, “Don’t you think you’d get tired of it?” But undeterred, the little one asks, “Every other day?”
The cast: Julie Andrews as Maria; Christopher Plummer as Captain von Trapp; Charmian Carr as Liesl von Trapp; Nicholas Hammond as Friedrich von Trapp; Heather Menzies as Louisa von Trapp; Duan Chase as Kurt von Trapp; Angela Cartwright as Brigitta von Trapp; Debbie Turner as Marta von Trapp; Kym Karath as Gretl von Trapp
See Robert Wise. The Sound of Music (1965). Screenplay by Ernest Lehman is based on The Sound of Music (1959); Music by Richard Rodgers, Lyrics by Oscar Hammerstein II, Book by Howard Lindsay and Russel Crouse is based on Maria von Trapp’s The Story of the Trapp Family Singers, and Wolfgang Liebeneiner’s film Die Trapp-Familie (1956); Wolfgang Liebeneiner. Die Trapp-Familie (1956). The screenplay by George Hurdalek and Herbert Reinecker is based on Maria von Trapp’s The Story of the von Trapp Family Singers. Philadelphia: Lippincott, 1950