Revealing mistake: When they first meet the Cowardly Lion, he jumps off of a boulder and obviously lands on a trampoline and jumps off.
Suggested correction: There is no trampoline visible. Sure, there is most definitely something he jumps off that is hidden behind the plants, but since we don't actually see it on screen, I don't see how it's a mistake.
Continuity mistake: When Toto pulls the curtain back to show who the real "Oz" truly is it looks like Toto's collar got snagged or he actually had to bite it but in the next shot he pulls the curtain back so fast that it would've sent Toto flying but then he is connected back to it again.
Continuity mistake: The Wicked Witch of the West's bilious green face colouring changes shades during the film. DVD showing.
Continuity mistake: The strand of straw that the crow pecks from the Scarecrow's lapel was not there before, as shown by previous close-ups. (00:36:00)
Revealing mistake: In the scene where the tornado is about to hit and Aunt Em and Uncle Henry are going into the cellar, you can see that some of the trees are blowing around violently, and others aren't moving at all. (00:16:05)
Continuity mistake: When Dorothy is holding Toto in the last scene, the dog is facing to the left, but in the very next shot he's suddenly facing to the right.
Revealing mistake: When they meet the Wizard for the first time, his big projected head doesn't reflect off the shiny floor, like everything else. (01:09:54)
Continuity mistake: When Glinda starts to sing, a Munchkin is seen coming out of an open sewer with its lid on the side. When the angle changes, the munchkin is nowhere to be seen and the sewer is closed.
Continuity mistake: When the cyclone arrives, the farmhands let out the horses, which run wild through the farm. In the immediate wide angle there's no sign of humans or animals anywhere.
Continuity mistake: When Dorothy extinguishes the fire on the Scarecrow's arm, the Witch keeps swapping between: close, far, next to a window, plain wall; all in a matter of seconds.
Continuity mistake: Miss Gulch rides away on her bike and Toto jumps directly off the back onto the dirt road. There should be tire marks on the dirt where he falls directly behind the bike, but there aren't. (00:10:30)
Revealing mistake: As the Tin Man busts down the Witch's door with his ax if you look closely you'll see a slight edit in the film right before he takes his last swing. What they did was unlock the door before the last swing so it would open. You can see the dead bolt retracted as the door swings open. (01:23:50)
Audio problem: When the Scarecrow says "You see, it's very tedious being stuck up here all day long with a pole up your back," his mouth is saying something else. (00:33:50)
Deliberate mistake: Before Dorothy is sent to Kansas there's a close-up of her shoes. All of the group's feet, Glinda's dress, and the rest of the elements around are gone and replaced by a black background. Despite being a deliberate directorial decision to give the shoes a more dramatic focus, it is really awkward to see everything disappear, nevertheless.
Continuity mistake: When Hunk hits his hand with the hammer there are two brooms leaning against the barn behind him. In the next shot they're gone. (00:03:45)
Visible crew/equipment: As the Wicked Witch stands on the balcony with the hour glass a cameraman's shadow can be seen moving across it near the hour glass. (01:24:15)
Visible crew/equipment: As the Wicked Witch prepares to leave for the Emerald City on her broomstick shadows appear on the painted wall depicting the sky behind her. (00:57:50)
Audio problem: When Toto escapes from the witch's castle and runs off to the Tin Man, the Scarecrow and the Lion to lead them to rescue Dorothy, he can be heard barking. As he is running up to the three, he is still barking, but his mouth is quite still and his tongue is hanging out. (01:19:30)
Visible crew/equipment: The apparatus on the Scarecrow's chest that's attached to the wires above his head can be seen sticking out in several shots as Dorothy walks up to him. (00:35:30)
