Revealing mistake: As they exit the Tin Man's scene singing, "We're off to see the Wizard", a bird stretching its wings is casting a shadow on the painted sound stage wall slightly to the right of the house, which reveals it to be a fake backdrop instead of an open area. (00:47:45)
Continuity mistake: When Glinda sings, "And Kansas she says is the name of her star" you can see the black manhole cover behind her and none of the Munchkins that are around it in the next shot are there. (00:23:15)
Continuity mistake: Just before the Wicked Witch leaves Munchkinland she says to Dorothy, "just try to stay out of my way" and her broomstick is facing upwards. In the next shot it's facing downwards. (00:30:35)
Revealing mistake: In the scene where the Lion sings his "If I Were King" song just before visiting the Wizard, if you watch closely above his moving tail, there is a string holding up and moving around the Lion's tail. (01:04:15)
Continuity mistake: Glinda tells Dorothy, "Their magic must be very powerfulÂ…" and Dorothy has her left hand around Toto. In the next shot she's holding the flowers in front of her. (00:30:20)
Continuity mistake: Inside the cyclone, looking out the window the wind is blowing left to right. In the room the wind is blowing in the window from the right. (00:18:05)
Visible crew/equipment: As Professor Marvel stands at the window looking at Dorothy and his fingers are curled under the sash. If you look closely they are lit up from underneath, but there's no light on their floor. (01:40:30)
Continuity mistake: Prof. Marvel reaches to open the door of his wagon as he walks Dorothy in. In the next shot the door is already open. (00:12:45)
Continuity mistake: After they first meet him when Dorothy pulls the Tin Man's arm down we see her dress and there's nothing on it. In the next shot there are several wet spots on the front of it. (00:41:55)
Continuity mistake: The Cowardly Lion says, "I'll fight you with one paw tied behind my back, I'll fight you standing on one foot." as he proceeds to put his arm behind his back and lift up his left leg. In the next shot his arm is out in front of him and his leg is on the ground. (00:49:35)
Continuity mistake: Before he is crowned, the Cowardly Lion has a blue flower next to his left ear. In the next shot it's gone. (01:06:00)
Visible crew/equipment: When Dorothy lands in Oz and exits the house to Munchkinland, the camera pans around the land. When it slowly pans over a large bed of tall flowers, you can clearly see a very large shadow passing over them. Obviously the shadow of camera equipment or a camera crane. (00:19:10)
Revealing mistake: When Toto reveals the Wizard by pulling the curtain aside, he doesn't use his mouth; the curtain is tied to the dog. Dorothy can even be seen later removing the rope.
Continuity mistake: There are two actresses playing Dorothy (and two dogs playing Toto) as she opens the door to Oz. The first is a stand-in wearing a dull colored dress in order to make it look black and white. After she opens the door and moves out of the way, Judy Garland is who we actually see walking through. Look at the different pleats on the two dresses. (00:19:25)
Continuity mistake: As Dorothy and the rest are chased by the flying monkeys the order of the four changes between shots each time we see them in the overhead shots. (01:15:10)
Continuity mistake: Just before getting crushed by the candle chandelier, the position the Witch's Guards are standing changes between shots. In one shot they're all standing apart, but in the very next shot, they all huddled together in one big group. (01:21:15)
Continuity mistake: When Dorothy runs to the back of the house during the storm the field in the background is not the same as we saw a few shots earlier as Aunt Em calls for her. (00:15:35 - 00:16:45)
Continuity mistake: The Scarecrow is in the lead as the four run away from the guards and enter the tower where the Wicked Witch is eventually melted. In the next shot the Tin Man is in front. (01:25:35)
Continuity mistake: When Dorothy walks up to the apple tree, the apple that she picks off of it, in the next shot is not there and after she picks the apple the remaining apples above her head disappear in the next few shots without being touched. (00:39:30)
Audio problem: When Dorothy and the Scarecrow find the apple trees she says, "Oh, look, apples." The overdub is wrong, if you look closely at her mouth when she turns around toward the camera, she's actually not saying anything. (00:39:20)
Suggested correction: Her mouth does move, and she actually says, "Oh, apples! Oh, look!"