I think it was the little girl feeding the zombies for sure, the first time I watched the scene I actually thought I saw a flash of a face
below the flashlight ( indicating it was a child holding the light up high ) but after re-watching it 3 times, I couldn't see it again. ( maybe it was lens flare :P ) Still, I really think there is something wrong with the child, when her sister said 'She's not weak, she's messed up' I think that was foreshadowing and I think Carol really misread the situation ; the kid really was upset about Nick dying. I have a feeling Carols decision to train the kids and now arm them without consulting any other adults is really going to come back and bite her in the ass.
Did more then one person die of the flu that night ? While clearing the prison they came to another cell with a bloody eyed zombie. There was a line about 'someone locked him in just in time,' to which Darryl replied the person in question locked themselves in every night because they sleep walk. If they don't ALL start locking themselves in now , it's going to feel like a huge plot hole to me, it's kind of hard to imagine they weren't already.
I have to agree with what has been said about the herd activity ; it's getting harder to accept how many zombies keep showing up ; assuming 100 zombies get cleared a day, over a 6 month period that's roughly 18 000 zombies. If they aren't clearing 100/day then why not ?
One thing that stood out to me in the first episode, why the heck were the zombies on the roof of the big spot not all clumped up on the edge of the roof closest to the direction the music is coming from??? They have suggested zombies just mindlessly shamble toward stimuli, and the dialog told us that this very stimuli worked for a big crowd of zombies on the ground, how come the ones on the roof were different? The music was still playing as they went through the fence, so even if the sound of breaking glass made them turn away from the edge of the roof briefly , following the 'mindlessly shamble toward stimuli' rule they should have turned back toward the music when the sound of breaking glass stopped. It seems to me , they could have had the zombies act in this manner and still told essentially the same story by moving the liquor isle to the same edge of the store.
Anyway

still loving the show, can't wait to see where things go with the final scene of this weeks episode.
Kytee