My only objection was how they were able to approach the house so easily, but I didn't take the drying swamp into account. Otherwise, I'm fine with it. MPH said earlier that there's a credible explanation for their appearance. Probably what we'll see in the last ep is a quick flash of various events over the last month, such as gunshots going off, and in each case, we see a few walkers turn and start shuffling toward the noise. And that pyre. Anyone notice they made a big point of showing the column of pyre smoke rising into the sky? This is where a whole bunch of little things come together ... resulting in a whole bunch of walkers coming together.