"Okay, so, the monsters in your world look creepier than mine and I didn't think that was even possible." Clementine pipes up from behind Joel, holding one of the toy gas masks in her hands and staring at the masks the same way he is.

From the outside this store had a lot of resemblance to her own which was what first drew Clementine inside. After a moment the resemblance started to make sense, given what Joel and Ellie had told her of where they'd come from.

Then she find Joel himself inside and feels reasonably confident in making that judgement that this is the store based off their world.