Indifference - S4-E4
Visible crew/equipment: During the scene where Daryl's group finds the auto shop, Daryl spits on his hand to wipe the window and is surprised by a zombie banging up against the window. He says, "Got some friends inside" and walks away. The camera pans to the window and a crew member wearing a white hat and (what appears to be) an orange shirt is visible in the reflection. He seems to be taking a picture (probably for continuity, which is pretty ironic). (00:09:50 - 00:33:05)
Visible crew/equipment: Andrea and the crowd are at Woodbury main gate arguing, when they hear a woman, closely followed by a man screaming up the street. Andrea and a lookout start to run up the road, where there is a woman running down the road. A sound-man in white shorts and red shirt, holding an overhead boom mic, is visible as he starts to jog down the street, tracking the woman as she moves towards them. (00:20:55)
Visible crew/equipment: Negan and Carl go for a ride in the big truck. Daryl tells Negan not to harm Carl and he flips him off. In this scene, the camera tracks upward and its shadow casts on the truck. Also a film light can be seen reflected in the door jam.
Visible crew/equipment: When the car flips in the chase scene, you can see the round canister used to flip it. (00:10:25)
Visible crew/equipment: When Sam comes to visit Carol with items in his hand, he walks through the front door of the house. Carol shuts the door after she lets him inside. As she does this, you can see the reflection of a black sheet or tarp of some kind covering the door area where the camera reflection would be.
Say the Word - S3-E5
Visible crew/equipment: Governor is 'interrogating' Michonne privately about staying at Woodbury to "join his forces." As he mentions Merle's name, she suddenly reacts, grabbing her sword from him, and shoves it at his throat, threateningly. During this, the shadow from the boom mic is visible just above his head. (00:13:50)
Pretty Much Dead Already - S2-E7
Visible crew/equipment: When Lori is cutting carrots and Shane is walking up to talk to her, look in the background behind Shane as he squats down. There is a person walking towards the barn.
Visible crew/equipment: You can see the casting directors on The Bridge behind Carol and Daryl wearing lime green vests. Then below The Bridge, you can see people driving their cars and a person walking in the parking lot. (00:26:57)
Visible crew/equipment: After Aaron refuses to provide his group's location, Rick tells everyone to eat and get some rest. When Michonne follows Rick outside it cuts to the car, and just as the camera pans to the right the actor's green nylon T-marker is visible on the ground, under the car door. (00:20:40)
Visible crew/equipment: After Judith tells Carol that her hair got really long Tara notices Lydia, and when it cuts to the shot facing Carol and Ezekiel, the white nylon T-marker is visible on the ground, between Lydia's feet. (00:08:25)
Visible crew/equipment: When Rick hugs his family, a crew member can be seen filming over the red car. (00:10:40)
Visible crew/equipment: Visible crew behind the tree towards which Carl walks back after replying to Hershel's "it was so peaceful" comment. (00:22:20)
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.