It was probably part of the score.
"Over the Rainbow"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Judy Garland
"'Come Out, Come Out, Wherever You Are', 'The House Began To Pitch', 'As Mayor of the Munchkin City', 'As Coroner, I Must Aver', 'Ding Dong The Witch is Dead', 'Lullaby League', 'Lollipop Guild' and 'We Welcome You to Munchkinland'"
(uncredited)
(Munchkinland Medley)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Judy Garland, Lorraine Bridges (dubbing Billie Burke), The King's Men Octet,
The Debutantes, Billy Bletcher, Pinto Colvig, Delos Jewkes, Abe Dinovitch,
, Betty Rome, Carol Tevis, Lois Clements, Zari Elmassian, Nick Angelo,
, Robert Bradford and Virgil Johanson (dubbing the Munchkins)
"Follow the Yellow Brick Road"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by The King's Men Octet, The Debutantes, Billy Bletcher, Pinto Colvig,
Delos Jewkes, Abe Dinovitch, Betty Rome, Carol Tevis, Lois Clements,
, Zari Elmassian, Nick Angelo, Robert Bradford, and Virgil Johanson (dubbing the Munchkins)
"You're Off to See the Wizard"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by The King's Men Octet, The Debutantes, Billy Bletcher, Pinto Colvig,
Delos Jewkes, Abe Dinovitch, Betty Rome, Carol Tevis, Lois Clements,
, Zari Elmassian, Nick Angelo, Robert Bradford, and Virgil Johanson (dubbing the Munchkins)
"If I Only Had a Brain"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Ray Bolger and Judy Garland
"We're Off to See the Wizard"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Judy Garland and Ray Bolger
"If I Only Had a Heart"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Jack Haley and the off-screen voice of Adriana Caselotti
Danced by Jack Haley
"We're Off To See The Wizard"
(uncredited)
Sung by Judy Garland, Ray Bolger and the off-screen voice of Buddy Ebsen as the Tin Man
"If I Only Had the Nerve/We're Off To See The Wizard"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Bert Lahr, Judy Garland, Ray Bolger, Jack Haley,
and the singing voice of Buddy Ebsen
"Optimistic Voices"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Performed by the offscreen voices of The Debutantes with The Rhythmettes
"The Merry Old Land of Oz"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Frank Morgan, Judy Garland, Ray Bolger, Jack Haley,
Bert Lahr and Emerald City Workers
"If I Were King of the Forest"
(uncredited)
Lyrics by E.Y. Harburg
Music by Harold Arlen
Sung by Bert Lahr, Judy Garland, Ray Bolger and Jack Haley
"The Happy Farmer"
(uncredited)
Music by Robert Schumann
Heard as background music during opening scene and in scene during which Toto runs back to Dorothy
Played by the M-G-M Studio Orchestra
"In the Shade of the Old Apple Tree"
(uncredited)
by Egbert Van Alstyne
Heard as background music during apple tree scene
Played by the M-G-M Studio Orchestra
"Night on Bald Mountain"
(uncredited)
by Modest Mussorgsky
Heard as background music while the group tries to flee the Witch's castle
Played by the M-G-M Studio Orchestra
"Home Sweet Home"
(uncredited)
from "Clari, The Maid of Milan" (uncredited)
Music by H.R. Bishop
Lyrics by John Howard Payne
Played by the M-G-M Orchestra as background music during final sequences of film
"Scherzo in E-Minor"
(uncredited)
by Felix Mendelssohn-Bartholdy
Played by the M-G-M Orchestra conducted by Herbert Stothart
Heard as background music during the scene in which Toto escapes from the Witch's castle and runs to fetch Dorothy's three friends