Continuity mistake: When the Tin Man, Scarecrow, Cowardly Lion and Dorothy are cornered in the witch's castle, the scarecrow grabs the Tin Man's axe and chops a rope, releasing the chandelier, which falls on the guards. In the next shot, however, as the witch is shrieking "seize them", the guards give chase with only 1 or 2 laying on the floor. (01:24:55)
Continuity mistake: After the Witch throws a fireball at the Scarecrow in the woods and disappears, Dorothy is holding Toto. But when it cuts to a closeup of her, it looks like her shoulders are extended. When it cuts back to the wide shot, she indeed has her arms around the Scarecrow and Tin Man, even though she never put Toto down. (00:46:55)
Continuity mistake: As the four go through the green doors to see the Wizard the hallway triples in length between shots. (01:08:40)
Continuity mistake: After Dorothy falls into the pig sty Zeke holds his left hand over the right side of his chest. In the next shot his hand is over the left side of his chest. (00:04:20)
Visible crew/equipment: As Dorothy and the Scarecrow dance off and sing, "We're off to see the Wizard" moving spot lights and equipment shadows can be seen on the grass on the right of the Yellow Brick Road. (00:39:00)
Audio problem: Just before Aunt Em and the others go into the storm cellar, Em calls for Dorothy and tells Henry she can't find her. Em's mouth never matches any of the words she is saying. (00:16:00)
Visible crew/equipment: As the door keeper tells them he will get them to the Wizard the camera shadow can be seen moving across the green door. (01:08:15)
Revealing mistake: As Dorothy skips off on her journey at the very end of the song "Follow the Yellow Brick Road", the shot cuts just in time to prevent her hitting the painted backdrop. The join between the ground and the backdrop is visible.
Continuity mistake: When the Wizard says, "Pay no attention to that man behind the curtain" he pulls the curtain closed and Toto's not there. In the next shot Toto's tied to the curtain again. (01:28:35)
Revealing mistake: In the scene when the Wicked Witch of the West bends down to retrieve the ruby shoes from the feet of her sister sticking out underneath Dorothy's house, there is one quick shot in the middle of the scene that shows her in front of a screen with a picture (film) of the house on it. Maybe that shot was filmed after the original set was unavailable? That would seem to be the only possible and reasonable explanation why such a shot would be necessary. (00:29:55)
Continuity mistake: When Dorothy first meets the scarecrow, there is a patch of grass in front of the field the scarecrow is in. On the grass there's two beds of flowers. The flowers change colors from when Dorothy meets the Scarecrow, to when the Scarecrow starts his "If only I had a Brain" song. (00:33:00 - 00:35:30)
Continuity mistake: During the storm the farm hands let the horses go and Dorothy runs to the back of the house as the wind blows directly in her face. If you look closely a large wood plank is sent sliding on the road, in the wrong direction into the wind. (00:15:50)
Revealing mistake: When Dorothy first meets the Scarecrow, he is placed up on a wooden stick and you can blatantly see the wire holding him up on it. (00:33:40)
Continuity mistake: Glinda says to Dorothy, "I'm afraid you've made a rather a bad enemy of the Wicked Witch of the WestÂ…" and the mayor of the Munchkin city walks up from behind them. In the next shot he re-approaches them from the left. (00:31:00)
Other mistake: In the close-up as the Wicked Witch pets him, Toto, who has been referred to as a "he" throughout the movie appears to be a she. In actuality, Toto is a female Cairn terrier. (01:16:05)
Continuity mistake: When the Tin Man is attacked by six flying monkeys they take away his axe. Several seconds later he has it again. (01:15:20)
Suggested correction: The "several seconds later" between his axe being taken and him having it back is a 25-second scene of the Scarecrow being pulled apart, and Dorothy and Toto being taken away. There was plenty of time for the Tin Man to retrieve his axe. Also, when we see the Tin Man with his axe again, there are still many flying monkeys on the ground, so it's possible that the flying monkey who took his axe didn't just immediately fly away with it.
Continuity mistake: When the Lion is singing about being King of the Forest, the Tin Man breaks a flower pot to "crown" him. Pay close attention, as the break marks on the pot change. In one shot there's a big jagged edge sticking up (obviously longer than the others) and in the next shot most of the edges are even.
Audio problem: Just before Dorothy lets the Scarecrow down, his lips don't match what he is saying. (00:35:35)
Audio problem: The talking trees throw their apples at Dorothy and the Scarecrow and if you look closely behind the tree on the right, Toto can be seen barking his head off, but we never hear a thing. (00:40:20)
Continuity mistake: When Dorothy first meets the Scarecrow there are no pumpkins on the left side of the Yellow Brick Road. Later when he starts to dance pumpkins have been added. (00:33:55 - 00:36:50)