They are clearly looking at something, even if we have no idea what it is. Are they at Terminus? That does not look like a train car wall, but we're hardly experts. Glenn's hair is a bit disheveled, and he has some scratches on his cheek. Is this right before Daryl (and maybe Glenn, and others) get bound and gagged? Glenn was tied to a chair in Season 3 and showed a walker who's boss. He also fought his way back into the prison after the Governor battle. So anyone messing with Glenn is entering a world of pain.
Maybe they are watching Rick as he peeks out of the train car? That's only if they are still in the car in this shot. They may be sneaking their way out of Terminus. Robert Kirkman said it would take ingenuity, creativity, and savageness to get out of the train car, but get out they shall. Several actors have now warned us that some brutal, disturbing stuff is coming, and they can't even believe it'll make it to air. That's meant to include stuff right in the premiere.
Are you ready to see the brutal great escape, and everything that comes afterward? If we all reach out and pull together, maybe we can grab October and make it get here faster.
The Walking Dead Season 5 premieres in October on AMC.