So I re-watched the ending last night and it was very strange. First of all, it does look like the compound is very well protected, the gates in front were the same height down the street as they go in, so i would imagine this same style all around. Second, when they pull up, there is no noise initially and you can't see anything moving behind the gate. Granted it was closed, but there were some cracks and an opening at the bottom, maybe there would be shadows. Then they focus on Rick's eye's and we hear the children playing. I am just wondering if Rick isn't just imagining the noise in hopes that they finally found a safe haven, somewhere where Judith will be safe. In the previews, they enter the compound with their weapons, another reason I can't believe there are many, if any, children in there.