What are your favorite Easter Eggs/nods to Wizard of Oz or the stage play?

I think one of my favorites is when Shizmistress Coddle refers to her not knowing about Elphaba as a slight “gulch” instead of glitch. This isn’t an “Oz” word, but rather a nice nod to Almira Gulch. The Kansas woman who later became the Wicked Witch (well, not “became” but you know what I mean. The Kansas version of her Dorothy knew)