I caught the full show. I got the impression that this was the brothers' first time in kilts. They didn't seem to care for it, commenting, "It's like a dress" or something similar. Their mom made them do it.

The guy wearing the kilt backwards was the BFOF. That clip appeared in promos but didn't make it into the cut of the show. I think that was from when they were getting fitted for tuxedos, one episode back.