Revealing mistake: Whenever Dorothy, the Scarecrow, the Tin Man, and the Lion go off into the horizon you can see the line on the floor of the sound stage where the fake horizon is and the scene cuts off right as the four get to that point. (00:57:35)
Character mistake: When Dorothy and the others enter the Haunted forest, the sign reads "Witches Castle One Mile." "Witches" is plural. To be grammatically correct, it should have said "Witch's Castle," if one witch, or "Witches' Castle" if more than one.
Visible crew/equipment: As Dorothy is leaving Munchkinland the shadow of the camera on its dolly can be seen on the floor to the right of the screen as several Munchkins almost get run over. The shadow of the cameraman's head can be seen on the bottom right of the screen as they pass her house. (00:33:15)
Visible crew/equipment: When the Wizard says, "Do you presume to criticize the great Oz?" look closely at the curtain as a crew member behind the curtain attaches it onto Toto so he can pull it open. (01:28:20)
Continuity mistake: Before they meet the Cowardly Lion, Dorothy starts to say "Lions and Tigers and Bears" and the axe jumps from the Tin Man's left hand to his right between shots. (00:48:20)
Continuity mistake: When Dorothy walks on the pig sty Zeke walks to his right, looks into, than passes the bucket on the right because it's empty. He then picks up the bucket behind it on the bench and proceeds to feed the pigs. He empties the first bucket then picks up the second empty bucket, which is now three quarters full. (00:03:55)
Continuity mistake: When the Lion, the Scarecrow, and the Tin Man are chopping down the witch's door to free Dorothy before the hourglass runs out, they are dressed in the guards' uniforms. We see the axe hit the door, and in the next wide shot they are not in the uniforms. There is a slight view of the uniforms in a pile on the floor, as if the trio had changed out of them between axe blows. (01:24:00)
Revealing mistake: As the cyclone carries the farmhouse through the air, it is evident that the walls of Dorothy's bedroom are not solid walls, but fabric-covered flats. They flutter and vibrate in the wind. (00:17:50)
Continuity mistake: Before the four go in to see the Wizard, and as they speak to him, Toto jumps from right to left between shots several times. (01:09:35)
Continuity mistake: When Dorothy first walks around Munchkinland, the bright ruby slippers are seen sticking out under the right window of the house. Later when the Munchkins come out we see the same spot again and the slippers aren't there. (00:20:40 - 00:23:15)
Revealing mistake: When Dorothy's bedroom is flying away to Oz, there's wind blowing everywhere and bits of hay falling. However, the hay is coming from inside the room, instead of outside, and the papers on the table next to the window don't blow away nor move an inch.
Continuity mistake: The bows in Dorothy's hair are tied differently throughout the scene with Glinda the witch in Munchkinland. (00:19:40 - 00:21:30)
Continuity mistake: The Wizard shouts, "I can't come back I don't know how it works" and the Scarecrow is on Dorothy's left. In the next shot he's on her right. (01:35:10)
Continuity mistake: In the beginning of the movie Miss Gulch parks her bike on the fence in front of the Gale's house and it's obvious that the fence continues in the same direction past the gate. When Dorothy comes back during the storm the fence now curves around right after the gate. (00:08:15 - 00:15:25)
Visible crew/equipment: Aunt Em gives Dorothy a cruller and says to her, "Â…and find yourself a place where you won't get into any trouble". Just as Aunt Em runs away you can see an equipment shadow fall across Dorothy's dress. (00:05:20)
Visible crew/equipment: Dorothy asks the Wicked Witch, "What are you gonna do with my dog? and a stage light shines against the painted backdrop outside her window. (01:16:20)
Character mistake: When the munchkin soldiers first arrive, you can see that some of the munchkins in the front are not beating their chest at the same time. This also happens when the munchkins sing the "fa la la la la" song before the witch arrives. (00:24:25)
Suggested correction: That happens in real life too with real soldiers and live performing actors as much as they try to perfect it because they're human, not machines. Unless there's a rule in the film that a munchkin has to be perfect and can't make mistakes like that, not seeing why this is a movie mistake when this is something that happens in real life.
Revealing mistake: You can see strings attached to the witches monkeys as they fly, and also strings from their bodies to their wings, to give the wings that flapping effect. (01:11:20)
Continuity mistake: As they enter the scene with the Cowardly Lion, the Scarecrow falls and then jumps over a patch of weeds growing in the middle of the Yellow Brick Road. In the next shot he does the exact same thing only about three feet behind the patch of weeds that he jumped over before. (00:48:00)
Continuity mistake: At the Witch's door the Tin Man is not the wearing his metal suit underneath the guards clothing. Look at his waist. (01:23:30)