Continuity mistake: When Scarecrow, Tin Man, and the Cowardly Lion are marching into the Wicked Witch's castle after taking the guards' uniforms, all three of them are shown holding the same types of spears as the guards, so when they go rescue Dorothy out of the locked room and Tin Man chops through the door with his axe, where did the axe come from? (01:22:50)
Suggested correction: I'm 63 years old and still watch The Wizard of Oz. If I remember correctly, the axe was taken off a nearby wall.
There is no scene of him taking the axe off the wall, nor is there any axe seen on any of the walls. Plus, it's the same axe he had the whole time. But the 3 also take off their coats/disguises while the camera is on Dorothy and it's possible he had the axe tucked away in the coat.
In the books, the Tin Man always has his axe and he uses it often. Perhaps it is the same in the movie.
Visible crew/equipment: As the talking trees throw their apples at Dorothy and the Scarecrow, look closely at the upper right hand side of the screen. An off camera crew member is shaking one of the trees back and forth as all of the others stand motionless. (00:40:20)
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!"
Audio problem: Inside the Emerald City Dorothy says "Can you even dye my eyes to match my gown?" Both the girl on the left and right reply but you only hear one voice speak. (01:01:35)
Suggested correction: Only the lady on the right replies.
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: 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.
Other mistake: When Dorothy's house is falling back to Kansas, just before it lands, there is about a 1 or 2 second shot of what looks like production notes written in blue ink.
Suggested correction: There are no production notes visible anywhere.
Continuity mistake: As Dorothy and the Scarecrow dance off and sing, "We're off to see the Wizard" the flowers that were on the fencepost have been removed. The stepladder by the fence has also been moved without being touched. (00:38:55)
Suggested correction: The flowers are still there.
Audio problem: As they all stand at the door to Oz, Dorothy reaches for the knocker and we hear the overdubbed knocking sound before she touches it. (00:58:45)
Suggested correction: The sound we hear before she starts knocking is of her grabbing the knocker, and it is right on time with when she grabs it. There is no audio mistake.
Plot hole: When the Gales' house lands in Munchkinland, Dorothy picks up Toto and glances around the house. She looks right out the window. Wouldn't she have noticed that she wasn't in Kansas then, before she got to the door? (00:19:05)
