Board Thread:Spoilers!/@comment-5899967-20150208192922/@comment-24674051-20150328203828

And if any actors are reprising recurring roles, it is quite likely that they won't be announced until the Press Release. They generally don't announce when actors return for existing roles. (Look how Jesse Schram kinda snuck up on us in the first half of the season.) Grumpy, Archie, Ruby, or any other standing member of the cast could appear without very much pomp (unless, of course, they choose to reveal it themselves).

For Instance, I saw a picture of Lee Arenberg with Agnes Bruckner (via both of their twitter accounts), and the impression, at least, was that it was taken at some point when both actors were in Vancouver filming OUaT. So while it is not conclusive, I would say that increases the odds that Grumpy is a part of Operation Mongoose. (Though someone else may have more conclusive evidence, I am just using this as an example). As another example, we have no Idea what Barclay Hope (established as Lily's dad back in 4A) is doing in "Best Laid Plans". He was not listed previously, and all we know for certain is his name is in the press release.

Probably about the only thing we can say for sure is nothing. However, there is a strong chance that there is no major role character being introduced into this episode, meaning that the filiming will use existing characters only.