Continuity mistake: In one of the most endearing scenes from one of the greatest movies of all times, nobody noticed that as Dorothy sings "Over the Rainbow" the haystack she's standing next to just materializes between shots. Later it disappears long before the twister reaches the house. If you watch the movie you'll see the exact spot where the haystack should be seen as Aunt Em gives Dorothy a cruller and says to her, "and find yourself a place where you won't get into any trouble". (00:07:25)
Continuity mistake: In the beginning of the movie Miss Gulch parks her bike on the fence in front of the Gale's house and it's obvious that the fence continues in the same direction past the gate. When Dorothy comes back during the storm the fence now curves around right after the gate. (00:08:15 - 00:15:25)
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)
Continuity mistake: There's a big mistake when we first see Prof. Marvel's wagon. If you look closely, the entrance steps that can be seen reflecting the light are upside down and would have to be set right before they could walk inside. (00:11:20)
Continuity mistake: When Professor Marvel guesses why Dorothy is running away, she's holding her suitcase with the lid facing Marvel. But in Toto's closeup, as he snatches the hotdog from Marvel's long grill fork, the suitcase is turned the opposite way with its lid facing Dorothy. Then it changes back, so the suitcase lid faces Marvel again. (00:12:10)
Continuity mistake: Prof. Marvel reaches to open the door of his wagon as he walks Dorothy in. In the next shot the door is already open. (00:12:45)
Continuity mistake: In the beginning, the fortune teller tells Dorothy to close her eyes, and he takes a picture of Auntie Em out of her basket. In the closeup of the picture, his hand holding the picture is not visible, although it should be. (00:13:20)
Continuity mistake: Outside of Prof. Marvel's trailer the wind is blowing strongly on him, but if you look under and behind the trailer the trees are not moving. (00:14:40)
Continuity mistake: When Dorothy runs to the back of the house during the storm the field in the background is not the same as we saw a few shots earlier as Aunt Em calls for her. (00:15:35 - 00:16:45)
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)
Continuity mistake: Just before Aunt Em and the others go into the storm cellar there are two glass jugs on top of the shelf on the right of their back door. When we see the spot again a few seconds later as Dorothy stands there the jugs are gone. They're not on the floor either. (00:16:40)
Continuity mistake: Just before Aunt Em and the others go into the storm cellar there are two glass jugs on top of the shelf on the right of their back door. When we see the spot again a few seconds later as Dorothy stands there the jugs are gone. They're not on the floor either. (00:16:40)
Continuity mistake: When the Wicked Witch tells Nikko "throw that basket in the river and drown him" The basket with Toto in it moves from one shot to the other in its position to the hourglass. (00:16:45)
Continuity mistake: Dorothy's house is outside of the tornado when we first see it up in the air. Then they are immediately inside the tornado. (00:17:15)
Continuity mistake: In the cyclone, Toto runs up to the window and barks at a cow. In the next shot Toto is gone. (00:18:00)
Continuity mistake: Inside the cyclone, looking out the window the wind is blowing left to right. In the room the wind is blowing in the window from the right. (00:18:05)
Continuity mistake: In the scene where the farmhouse is in the tornado, Dorothy is shown from behind with her pigtails in front of her shoulders. When the shot changes to the front, they are behind her shoulders. (00:18:05)
Continuity mistake: The house we see in the cyclone has all of it's windows intact. When it lands they're all out. (00:18:40)
Continuity mistake: When Dorothy first enters Munchkinland she steps out and in a front view we see her holding her hands close to herself, but when we look from behind, her hand is way out to the side. (00:18:50)
Continuity mistake: Dorothy's house just went threw a cyclone with chairs turned over, windows blown out and pictures knocked off the walls. Yet her comforter stays neatly folded and doesn't move from the bed. It's also changed and now has a plaid design on it. (00:19:05)
Answer: In the film it's left ambiguous. At the end it's strongly implied that she was dreaming. The characters she meets all look like people she actually knows. In the original book, she actually went to Oz.