Visible crew/equipment: After we first meet the three farmhands, Dorothy asks Zeke what to do about Miss Gulch. As he walks off to feed the pigs he steps into the camera's shadow. (00:03:20)
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 .
Continuity mistake: As Glinda's bubble appears Dorothy walks off camera but we still see her standing there as her shadow is on the yellow brick road. When we first see Glinda Dorothy's shadow just disappears. (00:21:30)
Continuity mistake: As she talks to the Scarecrow, Dorothy says to Toto, "Wasn't he pointing the other way?". In several of the close up shots wind is blowing her hair around and in others it isn't. (00:34:30)
Continuity mistake: As the Wicked Witch walks over to her sister a rocking chair is protruding through the broken window. In the next shot the window frame disappears and it's not a rocking chair anymore that's protruding from the window. (00:29:45)
Continuity mistake: As the Wicked Witch says, "It's so kind of you to visit me in my loneliness" a red penknife is on the ledge to their left. In the next shot it disappears. (01:16:10)
Continuity mistake: Dorothy's basket has been moved without anyone going near it after the Wicked Witch leaves the roof top. (00:46:20 - 00:47:30)
Continuity mistake: As they dance out of the poppy field, the snow that is on them disappears between shots. (00:57:35)
Continuity mistake: In the scene where the Scarecrow comes down off the pole and onto the yellow brick road, some of his stuffing falls out. You can then see Dorothy pick it up and put it back in. After Dorothy agrees to take the Scarecrow with her and they begin to skip away, you can see the straw that Dorothy supposedly picked up and put back inside the Scarecrow on the road again. (00:37:45)
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 the Scarecrow sings, " In trouble or in pain" Dorothy grabs him and is holding her basket with her left hand. In the next shot the basket is on her forearm. (00:36:55)
Continuity mistake: After the Wicked Witch leaves Munchkinland Dorothy is standing in front of Glinda one step below the top. In the next shot from behind she's two steps below Glinda. (00:30:55)
Continuity mistake: When Dorothy starts singing, "It really was no miracle " we see two Munchkins on the bridge. One in a red and white bonnet and the other has a distinctive blue hat. In the previous shot they are together on the other side of the stage on Dorothy's left. (00:23:40)
Visible crew/equipment: After they meet the cowardly lion and all four go off dancing and singing "We're Off to See the Wizard" a stage light flickers in the upper left background. (00:52:55)
Visible crew/equipment: Studio lights are reflected in the Wicked Witch's large crystal ball, as Dorothy sits down and cries beside it, just before she sees her Auntie in it. (01:15:10)
Plot hole: In the scene where the Wicked Witch is furious because Dorothy and pals have been saved from the poppy field, the Flying Monkey hands her a golden cap. She then dashes the cap across the room. The golden cap is used in the book to summon the Flying Monkeys. They shot scenes involving use of the cap, edited them out, but left this one with the cap inexplicably being tossed about. (00:57:05)
Continuity mistake: When they first meet the Tin Man a purple bird with a red beak appears and disappears several times near the house behind them. (00:41:20 - 00:42:20)
Continuity mistake: The Wizard holds the Lion's medal in his left hand when he takes it out of the bag. In the next shot it's in his right. (01:30:50)
Continuity mistake: As she holds Toto in her left hand, Dorothy looks around Munchkinland and says, "We must be over the rainbow". In the next shot she's holding him in both hands. (00:21:00)
Continuity mistake: When Dorothy first spots the Scarecrow the piece of rope hanging off his left arm is about 1 inch long. Without touching it a few shots later it's grown longer by about four or five inches. (00:34:30)
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.