Carrie: "Do you guys think maybe that is Abu Nazir in that other van with El Mysterioso? He said he wanted to be directly involved. And it would really fix like everything that is wrong with my life, if it were him. Think about it. Nick Brody gave him to us, so that whole heroic narrative could actually come true. And I would have stopped 9/11 Part II thanks to being the world's foremost Abu Nazir expert, so probably I could have my job back and not have to be under Quinn anymore. Maybe that delusional lie I told Brody was neither delusional nor a lie!"
Except, of course, that it depends on Abu Nazir being in the van. To be fair, it's very much like the one that Nick saw him go away in after their man-date that we don't really know what happened, so maybe he could be. It just seems unlikely that Abu Nazir would be chilling in this parking lot with a bunch of bombs, when he could be off doing higher-level stuff. Or even just admin stuff.
Saul: "Who's really running this operation, David? You? Or Dar Adal? And Quinn, who is he really? What are his orders?"
Estes: "He's here to kill terrorists, Saul. Just like all of us."
("This is a Nick Brody-Shooting hat, I said. I shoot Nick Brodys in this hat.")
Team Quinn finally orders the various tactical teams out, and everybody goes down in a freakin' hail of bullets, I can't even tell if Roya's okay but they storm the diner, they get everybody down, all the Team Mysterioso guys are dead, and just as Quinn's pulling up to a person's house in his limo-driving hat, Carrie flips over the driver of the van: Not the Sandman. Not Abu Nazir.
Which sucks, because how amazing would it be if you wrapped this shit up by 9 AM today, you know? But also, somehow when certainties fall apart things feel less solid than they would have if you'd never thought about it. You know? Like, if that guy really was the Sandman, the whole world would be different. Literally Carrie's entire life, small and harsh as it is, would be completely different. Winning the lottery different. And Nick would be the greatest hero, and they'd both be saved. Today could have been a very good day.
But instead, everything is uncertain. All those questions come back: Did Nick think Nazir would be there? Did he know for a fact he wasn't? Was Nick getting played? Was this all just a coincidence? Was this a Queen's Gambit, giving up Roya so that Nick would be stranded, or worse, desperate in the silence? Did they even stop the Big Event? Was this thing a trap they nearly fell into, or is something else -- Nazir loves this move too, right? -- is something else happening elsewhere and we didn't know. Because Brody planted the idea that it was worth blowing Roya's cover, taking her off the board, telling Walden about Nazir, all of it was worth it because today could have been a very good day.