I just watched it again; and a thought occurred to me: anyone think the Merle = traitor is a setup? We know that Merle told the Governor that he and his men had killed Michonne a couple of episodes ago; and we didn't see what transpired in the doctor's office after the Governor told Merle "I was attacked". We also didn't see how Daryl was taken. What if the two of them don't escape....just Merle.....because it was planned that way?
The Governor wants an inside man....anyone think that this whole thing is being staged; and Merle agreed to do it to save his own and his brother's life, given that the Governor knows that he lied about killing Michonne? We've already seen what the Governor is willing to do just to get information. I don't doubt that he'd make a threat like that to get Merle to do his bidding; and I don't doubt Merle would make the deal.
And what about the part in the preview when Herschel calls out to Rick "Get back here!"? I'm thinking that Rick offers himself as an exchange for Daryl (with Merle at the prison, secretly being the inside man). Once he's gone, and Merle has Daryl back, he sets out to destroy the group.
It'll be interesting to see how Andrea handles things, once she's face to face with her old crew and finds out more information. And if my theory is correct, it'll be interesting to see how Daryl handles the conflict, both internal and external.