From what we've heard, it sounds like Mulan and Ruby are only in this episode so far, Adam on twitter says "the plan" is to have them in more eps during the season, but it seems they're only in the 2 hour ep. for 5A.
Plus, this "adventure" may explain where Ruby and Mulan have been, and something tells me they might be the couple, Ruby had boyfriends in the past but I can accept this.
Though... wasn't Belle supposed to have an adventure with Merida for multiple episodes? What happened to that? Also, she is friends with both Ruby and Mulan so it WOULD work. I'm kinda sad she wasn't mentioned during the NYC interview. They would make a great team.