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: 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.
Continuity mistake: During the tornado scene at the farm Dorothy runs to the back of the house and the bench is turned over - when she returns the bench is upright .
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: When Glinda tells Dorothy to follow the yellow brick road, there are many Munchkins around. A second later, when she is about to vanish, they've all disappeared.
Factual error: If somebody fell into a pigsty, like Dorothy did, they would emerge covered in muck, but Dorothy emerges completely clean.
Continuity mistake: When the Witch melts, four guards suddenly appear behind her remains.
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: When Dorothy arrives in Munchkinland, she hugs Toto, but a frame later her right arm is extended.
Continuity mistake: When the Munchkin in purple tells Dorothy to follow the yellow brick road, Toto runs ahead of Dorothy. In the next shot he's back behind her.
Continuity mistake: In Munchkin Land, when the Witch threatens Dorothy and Toto, the way she holds her broom differs between shots.
Continuity mistake: When the Scarecrow falls on the yellow-brick road, Dorothy is not wearing her ruby slippers.
Continuity mistake: Back in Kansas, Dorothy holds Toto and her pigtails swap from being behind to in front.
Continuity mistake: The Munchkin Mayor's watch keeps changing time, from nearly to the hour, to twenty after the hour.
Continuity mistake: At the end of the movie, when Dorothy sits up, from the side shot her hair is shown going down her back, but in the front shot, her hair is in the front.
Continuity mistake: When the companions are walking down the corridor to the wizard's room, Toto is on their left side. Then, the camera view suddenly cuts to being behind them, and in which case, Toto is suddenly on their right side.
Revealing mistake: Throughout the movie, the tin man's costume wrinkles up.
Continuity mistake: When the Tin Man is telling his story, as he says "I was chopping that tree," Dorothy starts to look at the tree he's referring to, but in the next shot, she's looking right at the Tin Man again.
Continuity mistake: In the very beginning of the film, as Dorothy and Toto are running down the road towards the farm, you can see a small grease spot on Dorothy's apron when she reaches down to pick Toto up. When they reach the farm, somehow the spot has vanished.
Continuity mistake: In the poppy field, when Dorothy points at the Emerald City, the Lion is standing more than a meter away from her. In the close-up he stands very close to her.