Originally Posted by Buck
Yup, but it wasn't really an, "Oh shit!" moment.
We all already knew that Carrie knows it's Brody.
That's the thing, since she unwittingly successfully got the daughter to talk Brody down, she's utterly convinced that she had EVERYTHING wrong. That's why she's undergoing ECT. Don't forget she was in love with Brody too. So basically an unstable savante fell in love with someone she was convinced was a terrorist, only to turn out [apparently] he wasn't a terrorist and her conviction that he was has severed all ties to said love.
This is show that rewards paying attention. It can be taxing to keep track of what each character knows or thinks they know and why. But it presents a compelling tapestry where some people are objectively monsters or crackpots or rights violators or terrorists or powermongers, yet when you isolate the information each ACTUALLY has in hand, they are each in turn reacting at the very least quasi-rationally.