Continuity mistake: The hole in the wall Carol makes with the knife grows, depending on what angle we see it from.
Continuity mistake: Daryl is caught in a classroom and fights one of the Pope's men. He has him in a corner by the door where a walker comes. The walker gets killed by people on The Other Side of the door and it noticeably splatters on the glass. Two people break the door down and get inside. The splatter disappears on the glass.
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.