Principal photography concluded with the Kansas sequences on March 16, 1939. Reshoots and pickup shots were done through April and May and into June, under the direction of producer LeRoy. When the "Over the Rainbow" reprise was removed after subsequent test screenings in early June, Garland had to be brought back to reshoot the "Auntie Em, I'm frightened!" scene without the song. The footage of Blandick's Aunt Em, as shot by Vidor, had already been set aside for rear-projection work, and was reused.
After Hamilton's torturous experience with the Munchkinland elevator, she refused to do the pickups for the scene where she flies on a broomstick that billows smoke, so LeRoy had stunt double Betty Danko perform instead. Danko was severely injured when the smoke mechanism malfunctioned.[67]
At this point, the film began a long, arduous post-production. Herbert Stothart composed the film's background score, while A. Arnold Gillespie perfected the special effects, including many of the rear-projection shots. The MGM art department created matte paintings for many scene backgrounds.
A significant innovation planned for the film was the use of stencil printing for the transition to Technicolor. Each frame was to be hand-tinted to maintain the sepia tone. However, it was abandoned because it was too expensive and labor-intensive, and MGM used a simpler, less expensive technique: During the May reshoots, the inside of the farmhouse was painted sepia, and when Dorothy opens the door, it is not Garland, but her stand-in, Bobbie Koshay, wearing a sepia gingham dress, who then backs out of frame. Once the camera moves through the door, Garland steps back into frame in her bright blue gingham dress (as noted in DVD extras), and the sepia-painted door briefly tints her with the same color before she emerges from the house's shadow, into the bright glare of the Technicolor lighting. This also meant that the reshoots provided the first proper shot of Munchkinland. If one looks carefully, the brief cut to Dorothy looking around outside the house bisects a single long shot, from the inside of the doorway to the pan-around that finally ends in a reverse-angle as the ruins of the house are seen behind Dorothy and she comes to a stop at the foot of the small bridge.
Test screenings of the film began on June 5, 1939.[68] Oz initially ran nearly two hours long. In 1939, the average film ran for about 90 minutes. LeRoy and Fleming knew they needed to cut at least 15 minutes to get the film down to a manageable running time. Three sneak previews in San Bernardino, Pomona and San Luis Obispo, California, guided LeRoy and Fleming in the cutting. Among the many cuts were "The Jitterbug" number, the Scarecrow's elaborate dance sequence following "If I Only Had a Brain", reprises of "Over the Rainbow" and "Ding-Dong! The Witch Is Dead", and a number of smaller dialogue sequences. This left the final, mostly serious portion of the film with no songs, only the dramatic underscoring.
"Over the Rainbow" was almost deleted. MGM felt that it made the Kansas sequence too long, as well as being far over the heads of the target audience of children. The studio also thought that it was degrading for Garland to sing in a barnyard. LeRoy, uncredited associate producer Arthur Freed and director Fleming fought to keep it in, and they eventually won. The song went on to win the Academy Award for Best Original Song, and came to be identified so strongly with Garland herself that she made it her signature song.
After the preview in San Luis Obispo in early July, the film was officially released in August 1939 at its current 101-minute running time.
