In the ED they appear to add a "white rabbit" to their party.
I was frankly shocked when their first descent covered 850 meters. Given the way descent into the Abyss has been presented so far, I expected it would take an episode or two to go that far down. Maybe the journey was abridged to fit in the episode count?
Riko and Reg have a remarkably intimate physical relationship compared to most anime couples. It could be explained away by Reg being a "robot," but we all know he's fully equipped. Compared to a show like
where holding hands at the end is the culmination of the on-screen relationship, these two hold hands and hug each other all the time. So far their intimacy seems entirely innocent, and a consequence of their adventure, but it's certainly a change from many shows I've watched. Only Shin Sekai Yori comes to mind when it comes to twelve-year-old intimacy, but in that case it's a part of the story line.