Rather than No.V looking like Rein, she looks more like...
Or if you want to think it in another way, the Small Boss joke might've caught on the director.
@Thisguy, I don't know if you've caught it, but the one with No. III with it's boomerang-ish IS is VII, not XII. I've rewatched, and Tre clearly addressed her as Sette. Granted, no. XII, Dido was also mentioned, but that's merely by Uno before the mission officially started, meaning that's XII's somewhere...ready...but not yet shown.