Audio problem: In the scene when Andrea is mourning the death of her sister, Rick walks up to "tell her how it is." Andrea points a gun at Rick with just her right hand. When the gun is coming up to Rick we hear the slide being cocked, this can only be done with two hands. (00:03:35)
When the Dead Come Knocking - S3-E7
Audio problem: When Rick and his 'strike force' hole up in the cabin surrounded by walkers. They arouse the cabin's owner who brandishes a double-barrel, breech breaking shotgun. When characters brandish pump action shotguns, often they pump a round for effect and the sound effect is characteristic. The pump action sound effect is erroneously applied to the breech breaking double barrel shotgun.
Chokepoint - S9-E13
Audio problem: Lydia is hammering a nail in a board trying to barricade a door. The sound of the hammer hitting the nail is slightly off.
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.