Some fun things I noticed in EAH that might be unintentionally references to the original stories:
The choice to have Hopper as Briar's suitor makes sense on two levels. First, because in the Grimm version, a frog announces Beauty's birth. Second, the Grimm version's frog prince fails to win the princess's heart. In both cases, there's a genetic component to Hopper's attraction to her.
Cedar in one episode said "The branch of my family" Pinocchio, in Collodi's story, is indeed born from a magical tree.
Blondie claims her family has royal blood: this is technically true! The Story of (princess) Pretty Goldilocks is a real fairy tale by Madame D'Anuloy. Not only that, but Goldilocks's lover is named Charming.
Holly has a lion cub, and says that pet lions are common in their kingdom—in Basile's version of Rapunzel, she's able to summon a lion by planting a seed.
In Alice Through the Looking Glass, one of the Queen of Hearts's servants is Ugly Duchess, owner of the Cheshire Cat. It makes sense, then, that Duchess is Lizzie's roommate and Kitty's friend.
In Alexander Dumas's "Robin Hood - Prince of Thieves," which is the text usually referred to when adapting Robin Hood, it is said that despite being only sixteen years old, Robin looks older: This match with Sparrow design! He is the only boy with a beard, and in fact he seems older than the other boys despite being their peers.