GW vs American
 

R2 just erroneously gave a discrete "back row" signal on a Team A attack, which the R1 ignored. Play continued and Team B won the point when the ball went out of bounds. But the announcer was very confused and the Team A coach wanted a replay because he thought the point was awarded for an illegal back row attack.

If they're wearing headsets, what is that conversation like? The conversation with the coach is easy. But does the R1 say anything or just continue to officiate the play without comment?

Did R1 ignore it, or shake it off (or discuss on the headset)? (probably hard to tell on TV).

Why was it not a BRA (what did R2 "see" in error)?

I didn't see a shake off, seemed like it was just ignored. I think the R2 thought the setter was back row when she was actually front row. That's why the coach wanted a replay. He knew she was front row and thought the call had been BRA.

I assume they had headsets, but couldn't be sure on TV. I have no idea what the conversation was (if there was one). I was sort of hoping Felix would offer some perspective.

I didn't see it, and I'm too lazy to look it up, so I'll speak generically.

As far as what that communication can look like (and every conversation is different), the R2 can say "Back row" and the R1 can reply "She's front row." If they correctly let is play out, then no harm. Mistakes happen.