Revealing mistake: After the witch says "Hey scarecrow, wanna play ball" she throws a fireball at him. But you can see the ground catch on fire before the fireball hits the ground. (00:46:20)
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)
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)
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.
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)
Revealing mistake: During some scenes, straw-stuffed Scarecrow's pant legs and his boots would sometimes have a gap that reveals the skin of Ray Bolger's leg. Two examples are, at Emerald City when Scarecrow places Lion's "cape" on him, and also when Dorothy and her friends are told the Wizard says to go away. (01:05:50 - 01:07:25)
Revealing mistake: When it starts to snow in the poppy field, Dorothy falls asleep, followed by the lion. In many of the later shots, a thin wire attached to the lion is visible the entire time.
Revealing mistake: When the house lands in Oz, it lands with a bump and Dorothy is laying on her bed with Toto. The objects in the room had moved about a lot due to the twister, and wires attached to the end of the bed and the chair, etc. are really quite clear. (00:18:12)
Revealing mistake: As the Wicked Witch throws the hour glass down at them the stone statue on the left of the monkey is shaking. (01:24:45)
Suggested correction: It's the monkey that is shaking, not the statue.
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.
Revealing mistake: After the Wicked Witch throws fire down at them the Scarecrow kicks the stump next to him and it moves several times. The one behind him also moves. (00:46:25)
Revealing mistake: The candles on the chandelier that fall on the guards are not real. If you look closely at them they're operated with gas. (01:24:50)
Revealing mistake: As the Wicked Witch chases the four yelling "Seize them," they run around what looks like a concrete pillar. If you look closely it's covered with cloth that moves as they run by. (01:25:00)
Revealing mistake: After the Wicked Witch exits Munchkinland in a puff of red smoke and flames, you can briefly see sulphur marks left on the trapdoor. (00:31:00)
Revealing mistake: The Scarecrow tells Dorothy to, "just bend the nail down in the back and maybe I'll slip off" but what she actually does is pull a lever. (00:35:40)
Revealing mistake: After the doorman tells the four they can't go see the wizard he returns back into the palace and you can see his shadow where it shouldn't be against the painted backdrop wall inside the door on the left. (01:07:25)
Revealing mistake: In the Haunted Forest, when the Tin Man is lifted up then lands back on the ground, at Tin Man's lower back you can see his white T-shirt tucked into his pants. (01:14:10)
Revealing mistake: Throughout the movie, the tin man's costume wrinkles up.
Revealing mistake: The glass in Dorothy's bedroom windows don't break, they are removed from their frames as the scene progresses, and if you look at the reflections in them the windows are made of plastic. (00:18:45)
Revealing mistake: When they first meet the Cowardly Lion, he jumps off of a boulder and obviously lands on a trampoline and jumps off.
