After Dorothy is awakened by the Tin Man's tears, she sits up and wipes her face with both hands. In the next shot, however, when Toto awakens, Dorothy is still sleeping because her hands and arms are still down.
The scarecrow is still learning how to walk after he got down from the pole. When Dorothy runs to the taxis, the scarecrow walks perfectly to another place behind Dorothy. When they sing "Ease on down the road," the scarecrow is sill trying to walk to the Yellow Brick Road.
When the Tin Man is finishing his dance to "Slide Some Oil to Me," he is near mirrors, alone, with his hat off. When the Tin Man starts to sing "Ease On Down the Road," he is away from the mirrors, with the Scarecrow and Dorothy with hat on in the next shot.
During the wide shot in "Slide Some Oil to Me" when Nipsy Russell is dancing in front of the mirrors, there's a large hole in the canvas behind him. You can see a camera through the hole, and a couple of times, you can see a reflection of him dancing in the camera lens.
Aunt Emma comments that Dorothy has never been south of 125th Street in the Manhattan neighborhood of Harlem. However, Dorothy later gives her address as being on Prospect Place, which is in Brooklyn, miles southeast of Harlem.
When the Red people are dancing in front of a camera at the Emerald City, there is a giant screen that shows the people dancing. A red woman goes in front of the people and does a dance, but her movement on the screen does not match the moves that she makes in front of the camera.
In the scene just after the Cowardly Lion joins the group, all four of them do a dance that begins with them walking over some taxis, and one of them clearly bounces somewhat, revealing that they're inflatables.