Pretty Much Dead Already - S2-E7
Continuity mistake: As the group kills the walkers that come out of the barn, the camera shows several different vantage points from in front of the barn, inside of the barn etc., it shows the walkers lying with a clear path between them, and in another it shows the walkers lying in a jumbled pile with no path between them. This goes back and forth a few times until Sophia comes out of the barn, and there is no clear path again.
Pretty Much Dead Already - S2-E7
Continuity mistake: As Daryl and Shane argue near the start, Daryl's movements don't correspond with the changing shots: one moment he is standing in front of Carol, then he is standing by her, then he has moved closer to Rick - all within the same one-liners. As his argument with Shane grows, he again is standing by Carol, or closer, near Rick. At one point, a shot shows Daryl about to lounge at Shane, as Rick blocks him, but the very next shot shows him right next to Carol, who at that point would have been standing behind Rick. (00:10:00 - 00:11:00)
Pretty Much Dead Already - S2-E7
Continuity mistake: After Carol tells Shane they are not leaving without finding Sophia, Daryl enters and reminds Shane about the doll he found down at the swamp earlier, and they start to argue. During this he crosses front to Carol's right. In the very next shot Daryl is suddenly shown standing in the same spot as prior, next to Carol. (00:10:00)
Pretty Much Dead Already - S2-E7
Continuity mistake: After talking with Hershel, Rick heads out to the barn and meets up with Shane at a tractor. Shane asks him which way is it going to go as Rick is looking to his left down at the tractor. When the shot cuts to The Other Side as Rick responds, he's suddenly looking straight ahead at the barn. (00:15:32)
Pretty Much Dead Already - S2-E7
Continuity mistake: Rick is talking with Hershel in his kitchen and asks him to please not send Them out into the world again. Hershel is looking down at his sink from the side angle. When it cuts to a view from behind, he's suddenly looking up to the left out of the window, only to lower his head back down towards the sink again. (00:13:57)
Pretty Much Dead Already - S2-E7
Continuity mistake: When Shane finds Dale in the swamp trying to hide the guns, when he first sees Dale, Dale is holding a large spike to drive into the tree. In the next second they show Dale standing next to the tree with the spike already in it.
Pretty Much Dead Already - S2-E7
Continuity mistake: Deleted footage/special release only: Carol confronts Daryl about the boy being held hostage inside the barn (following Sophia's death), reasoning with him about pretending not to care when he truly does. At one point he moves to her, almost in her face. However, the following shot shows only a close up of Carol, implying they are standing feet apart, which is not the case. (00:24:10)
Answer: Walkers are attracted to noise, they can tell who's dead and who isn't dead, in S1 when Rick and Glenn cover themselves in walkers' guts they're able to get far by walking through the herd of walkers because they smell like they're dead, but as soon as the guts get washed off by the rain the walkers immediately attack them, if you draw attention to yourself they will attack you which we've seen that many times throughout the series that it's not always successful. Whether you're covered in guts hiding under dead corpses or under a car.