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.
Continuity mistake: When the Winnebago breaks down. Shane and T-Dog offer to drive ahead to check out what could possibly be a gas station. Shane tells Rick to hold the fort while they're gone. Meanwhile Rick is dealing with dying Jim. When discussing Jim's predicament, Shane is there, he hasn't gone anywhere. Then when they put Jim under the tree T-Dog is there too. Then they all drive off like the breakdown never happened. Nothing is mentioned about whether Shane and T-Dog found a gas station and if they did, it was very quickly sorted out - two minutes tops. (00:31:00)
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.
Continuity mistake: When Mica and Lizzie are running from the walkers on the railroad tracks, they easily outrun them and gain several meters' distance in a few seconds. When they are running to the house, the walkers have suddenly caught up and are directly behind them.
Revealing mistake: When Carl rolls out the knife pack he found, the scene cuts to Shane working on the engine, and you can see traffic on a highway through the bottom of the windshield. (00:33:00 - 00:34:00)
When the Dead Come Knocking - S3-E7
Continuity mistake: The first shot of Maggie waiting for the Governor to enter shows her wearing a black tank top with her shoulders bare. After he cuts the duct tape around her wrists, the camera pans up and she now has black bra straps showing on her shoulders. (00:26:10)
Other mistake: When Daryl is cutting open a walker in the woods to see what meat it ate while searching for Sophia he stabs the walker several times, but the knife is not bloody and it stays clean. (00:33:30)
Continuity mistake: When Glenn is with Tara and getting ready to move out, he puts on his helmet and you can see it is strapped on. When the shot changes, he swings the fence open and you can see his strap is lose. The camera angle changes again and the strap is back on again. (00:38:15)
Visible crew/equipment: When the car flips in the chase scene, you can see the round canister used to flip it. (00:10:25)
Internment - S4-E5
Continuity mistake: When Rick gets out of his car and talks to Maggie inside the prison gates. The car door opens and shuts throughout the conversation.
Continuity mistake: In the flashback to the prison, Hershel says "we've been here two months." However, when they show Judith she is shown to be the same age she was when the prison fell (around 9-10 months) If they had only been there two months, and Lori delivered within the first week of being there, the baby should not be very old.
Chupacabra - S2-E5
Continuity mistake: During the scene where Norman Reedus is talking to Michael Rooker, watch the dirt and sand around Reedus' mouth appear and disappear during the talk while he is on his back.
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.
Continuity mistake: In Season 2 episode 7, "Pretty Much Dead Already," at the end where Rick shoots the walker Sophia, she falls to her right. In the next episode, "Nebraska," picking up immediately after the last, she is in an entirely different position, as if she fell forward.
Factual error: Ten minutes into the episode, where they're setting up their police-blockade, a cop makes a remark about being in some TV-show when Rick Grimes replies with: "Make sure you've got a round in the chamber and your safety off". Next we see the first cop checking his gun (a Glock) for a round in the chamber and we see him flicking his thumb across the gun's slide catch: not a safety-lever. Glocks don't have an external safety, so the cop cannot flick a safety-lever like in the episode. (00:10:10)
Factual error: The supposedly American tank Rick crawls into in Atlanta has US markings but is a British Chieftain.
Plot hole: Diana in her final scene is seen shooting her last bullets at the walkers that are offscreen, moving toward her, so suicide was not an option, meaning the walkers would have eaten her until she died, becoming a walker. And yet her body is completely clean when her son and Michone discover her in walker form. Blood free (even on her clothes) and fully intact, no chunks of her missing, no bite marks.
Character mistake: At the very end of the episode Tara tells Glenn that her sister and nephew were not supposed to be there. Tara had a niece not a nephew.
Answer: The walkers could have knocked them down more than once. There may have been another wave that knocked down the fence earlier and they're going to put it up again soon.
Captain Defenestrator