The overthinker in me – and I'm not the only one – was slightly confused by this and how they would present it. If you remember, Henry came to learn about Storybrooke's "history" via a book of fairy tales. Cinderella, Snow White, Sleeping Beauty, and other classics. (Apparently, that includes Mulan....)
Now, Frozen is not a classic fairy tale (at least, as far as I know). In fact, it isn't even based on any kind of folklore or history of any kind, as say, Mulan or Sleeping Beauty is. CORRECTION – Nik let me know that it is based on The Snow Queen by Hans Christian Anderson.
More than that though, Frozen was not even out in theaters when Henry, Emma and friends "remembered" who they were. Did they see the movie? I'd think no... unless they stopped by the movie theater one lazy Sunday afternoon between defeating evil witches and
Basically, do the people of Storybrooke even know who the Frozen princesses are?
This has been debated across the interwebs, and it would assume, of course that OUAT takes place in the present day. TV Line has an interview with showrunners about it, in which they confirm that no, Henry has not seen Frozen. By their calculations, the people of Storybrooke are somewhere in 2013 right now, pre-Frozen release.
But looking at these previews for the new season, it seems like Emma may recognize the sisters... or maybe it is just ABC toying with us as usual.
Speaking of new characters / princesses from recent Disney pictures, where the heck are Tiana and Prince Naveen? I understand that OUAT isn't keen on talking animals/objects – made that clear with the exclusion of Olaf in the upcoming season – but is Naveen's talking frog much different than Jiminy Cricket who has been featured at great lengths in both human and cricket form? We need some diversity in Storybrooke.