Continuity mistake: When Daryl is driving the hospital van, it shows that he is going to land upside down, on the vehicle's roof, when he drives off the parking garage. In the next scene, the vehicle lands on its wheels, as if it has done a complete front flip. (00:30:00)
No Sanctuary - S5-E1
Continuity mistake: At the start of the episode when Tyreese and Carol are walking down the railroad tracks towards Terminus, they encounter a herd of walkers coming out of the woods. One of the first walkers to cross the tracks is a male walker wearing a burgundy sweatshirt with a rip in the middle. When gunfire erupts at Terminus, the walkers turn their attention towards it. In the next shot when they start to head towards the sound, we see the same male walker now in the middle of the herd yet to cross the tracks, next shot after that, we again see him at the front of the pack.
Continuity mistake: When Beth is looking for a key in Officer Dawn's office, she encounters Joan lying dead in the office from bleeding out, apparently from suicide with a pair of surgical scissors. Her left hand is covered in blood. But when Officer Gorman enters the room and Joan starts to turn into a walker, the blood on her hand has disappeared.
Continuity mistake: Maggie pulls the ladder from the rear of the firetruck, but in previous shots the only ladder on the firetruck is hung on the passenger side.
No Sanctuary - S5-E1
Continuity mistake: Near the end when Rick thanks Tyreese, the cabin door is open after Tyreese had closed it as the group walked up. In next shot it is closed again.
What Happened and What's Going On - S5-E9
Continuity mistake: Tyreese, Noah, Rick, Glenn and Michonne all go to see Noah's old base in search of his family. Tyreese gets bit, and they begin to run back to the car. Except for one tiny clip, Daryl is running alongside them, even though he was with the other half of the group. (00:33:15 - 00:33:40)
Continuity mistake: When Jessie brings a basket of stuff to Rick the paper towels are on her right, then when Rick takes the basket they're on her left, and then in the next shot they're back on her right.
Continuity mistake: Possible Spoilers! At the very end of the episode Rick walks up to the wall of Alexandria to check out a noise. When the camera shows the walker on The Other Side of the fence it is clear there is nothing else out there. When the camera shows the fence from behind Rick there is the roof of a house visible above the top of the fence. The shadows made by the struts of the fence make it apparent that if there was a house The Other Side of the fence would have been in shadow. (00:48:00 - 00:50:00)
Continuity mistake: Arriving at Alexandria, Rick is shown from an interior POV leaning into the back of the car and picking up Judith, who is mostly wrapped in a spotty shawl. As he is shown doing this from an exterior POV, the shawl is barely visible, bunched up behind her legs. (00:41:44)
Continuity mistake: When Aaron and Daryl are stuck in the van surrounded by walkers, he lights up a cigarette with a yellow filter and it changes to a white filter as he starts smoking it.
Continuity mistake: Gabriel burns his collar while eating at the side of the road, however when trying to stop the barn doors opening in The Storm it is back again.
Continuity mistake: At the end 3 men go to rush Rick - the guy on the right is Glenn. All three men are standing shoulder to shoulder when Rick pulls his gun, and Glenn has disappeared. Cut back to Rick and a wide shot - no Glenn. Cut to a close up of the group and Glenn's back, but there is a big gap between him and the other two men. This scene is continuous - he hasn't got time to move.
Continuity mistake: Sasha is pinned by the walker, but saved by Michonne. As she is standing up, the leaves in her hair disappear between shots.
Continuity mistake: At the end of the previous episode, Daryl leaves on a motorbike with a car following. In this episode Daryl's still out but no bike - he's in a car. It's a continuous trip with the bike he built at the compound.
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.