I read RM said that the twist was we would see behind the camera and the real thing that propels the rest of the season comes around the 40 min mark and that is when the script read that only 1 person survives.
TWIN PEAKSBATES MOTELAHS**HANNIBALHUMANS*MR ROBOT

I don't feel like this season has had all that much actual horror. Plenty of jump scares and sudden eventslike the historian getting his head bashed in with the hammer.
So much of it has just been the pigman suddenly popping up.

It wasn't really a twist, it was just a plot advancement. RM is pretty arrogant when it comes to these things.
Apparently, Finn Witrock (?) is playing the most messed up character "EVER" - RM just likes hyperboles to get attention.
That being said, this season is spectacular. It hasn't been this creepy since Asylum. It's finally back to actual horror instead of a 13 hour long hot topic commercial.

We weren't invested in the sequel to MRN. I thought the twist was supposed to be something that subverted everything we'd seen so far.

1. I agree, but I
   assumed
   we were watching the sequel, nonetheless.
2. RM tends towards hyperbole.
   Dude, its Beacon Hills.

I'm still not sure that's it. We weren't invested in the sequel to MRN. I thought the twist was supposed to be something that subverted everything we'd seen so far.
I think the twist was that we weren't watching MRN in "real time"as it was being made/recounted, but we had been seeing something that was already complete. I don't know. Nothing happened in this episode that was shocking or challenge anything we've seen so far.
Maybe because everyone has been discussing it so much and has brought up theories that I had it in mind already that the documentary series we were seeing wasn't the entire story.

What I mean is, the reveal that the second docudrama (that we thought we were watching) was not, in fact, the show.
Up to that point we thought we were watching the sequel to MRN.
Dude, its Beacon Hills.

That was directly stated during the episode. I don't think that's a twist.