Board Thread:Character Discussion/@comment-24138799-20140428211612/@comment-25562278-20141023143131

I don't think Oz was planned out in advance though. As far as I remember, there wasn't a lead in to Zelena's arc like there was with Cora, Neverland, and Frozen. It felt like they knew they wanted to do Frozen, but needed something before that to lead into the reason why Elsa would be in Storybrooke.