Pretty Much Dead Already - S2-E7
Other mistake: As Daryl carries a saddle toward the barn, in the far shot, there is no one around. The shot then changes to him entering the barn carrying the saddle inside. Suddenly we now see Carol coming around the corner, several yards behind him. Where did she come from? Unless she was already inside next door and saw him enter, she shouldn't have been there.
Answer: The walkers could have knocked them down more than once. There may have been another wave that knocked down the fence earlier and they're going to put it up again soon.
Captain Defenestrator