Role in the film
Alice was following the White Rabbit through the hallway, and then through a few doors, leading to a small hole, and she crawls through and finds herself in the exterior. She feels curious, about finding a colorful wide open room being completely empty.
Alice heard a sound coming from small curtains straight to the front of the exterior. She ran towards it to open the curtains, and meets the Doorknob. She told the Doorknob that she was looking for the White Rabbit, and if he doesn't mind letting her look through his keyhole. The Doorknob tells her that she's too big to get through, which a table magically appeared along with a bottle that causes Alice to shrink to the right size. The Doorknob then claims that he's locked.
The key appears after the Doorknob asks Alice if she left it on the table. Alice then tried to climb the table, but it was too slippery. A box full of "Eat Me" cookies appears, and Alice eats one, which causes her to grow to a giant size. Her seemingly inescapable situation results in her starting to cry, which her large tears start to flood the exterior. She drinks the bottle again, and not only shrinks, but traps herself in the bottle as well, traveling through the Doorknob's mouth and venturing further into the rest of Wonderland.