Visible crew/equipment: When Billina and Dorothy are stuck in the crate, when Billina says "how's my grammar," you can see a wooden board has been nailed to the crate to cover up the spaces in between the bars, so that the puppeteer can crouch down and control Billina. (00:23:00)
Visible crew/equipment: After just meeting Tik-Tok, Dorothy winds him up, and then he bows, and raises his hat. As he bows a crewmember can clearly be seen crouched behind him. (00:36:20)
Visible crew/equipment: When Tik Tok is spinning around and hitting the Wheelers with the lunch pail, a camera and crewmember are reflected in the shiny copper of Tik Tok's front. (00:37:50)
Visible crew/equipment: When Mombi leads Dorothy into the 'head' room, as the camera moves along a crewmember in a pink shirt, wearing glasses, is reflected in the glass screens of the head cases. (00:41:40)
Visible crew/equipment: As the camera is panning around to show off the variety of heads Mombi has collected, in one shot you can see the reflection of the cameraman with a camera in one of the glass screens. (00:41:50)
Visible crew/equipment: When Dorothy is opening the mirrored door to Mombi's bedroom, as she pulls the door open, a crewmember in jeans and a white tee-shirt is momentarily reflected in it. (00:50:10)
Visible crew/equipment: When Billina lands on the couch with the cord, as she flies down some mechanism controlling her can be seen, attached to her feet and legs. (00:50:50)
Visible crew/equipment: When Jack's head falls off, it is flying in the air, near the couch. Two black wires holding it up are visible. (01:01:25)
Visible crew/equipment: Wires are clearly visible attached to Dorothy's shoulders, Jack Pumpkinhead's pumpkin head and his body, as everyone falls down from the sky after the couch goes bonkers. (01:02:05)
Visible crew/equipment: When Dorothy falls down into the Nome Kings lair, she falls to the floor and slides along into the scarecrow. The black sled she is sliding on is momentarily visible as she passes the camera. (01:07:05)
Visible crew/equipment: When the Nome King says "I know something which will cheer you up," it cuts to Jack Pumpkinhead and Tik Tok sliding along the ground. The track which is sliding them along is visible. (01:08:55)
Visible crew/equipment: When Dorothy, Tik Tok and Jack are eating and drinking in the Nome King's lair, Tik Tok says "What is it we are risking?", and there is a small explosion, causing the table to fall, and them to all fall back. A wire attached to the table to make it fall is visible to the right of the screen. (01:11:50)
Visible crew/equipment: When Dorothy first enters the room full of ornaments, the camera pans backwards, away from her. The camera passes tables of ornaments. Watch the large blue vase to the right of the screen, and a cameraman can be seen reflected in it, walking backwards with the camera. (01:18:45)
Visible crew/equipment: After Billina lays an egg in the Nome Kings mouth, the King drops Jack Pumpkinhead to the floor, and wires attached to him, out at the side, are visible to let him down gently. (01:28:55)
Visible crew/equipment: After Dorothy returns from Oz, we see her laying on the leaves in the woods. In an extreme closeup of her eyes, the camera is reflected in them. (01:37:10)
Visible crew/equipment: When Dorothy is strapped down to the pedestal by the doctors, they then proceed to push her down the hallway, and pass the camera on their way. As they pass, the camera casts a clear shadow on the sheet covering Dorothy.
Visible crew/equipment: When Dorothy is speaking to Aunt Em about the key she found, Aunt Em says "That legs mended, it's mended..." then she gets up and passes the camera, which casts a clear shadow on her as she walks past it.
Visible crew/equipment: In shots of Dorothy and Ozma running away from the doctor's clinic, there is a noticeable outline of kneepads under their dresses, and as Ozma slips down the muddy bank, and into the river, her dress momentarily rides up, revealing it quickly.
Answer: She was in the human world so she was in disguise.