The Yellow Brick Line is a metro line built on what was once the Yellow Brick Road, one of Emerald City's oldest and most storied roads.
The Tin Woodman/Tin Man is only represented as a comic book hero thus far. However, the cover reveals that it is based on a true story.
Ojo is inspired by a character in Baum's books: a munchkin boy named Ojo the Unlucky, who first appeared in The Patchwork Girl of Oz.
Patchwork Doll is inspired by the Patchwork Girl, a character from Baum's books who is a living doll made of various scraps.
Dorothy's outfit is an inversion of her namesake's: ruby shirt and blue & white checkered shoes.