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)
Other mistake: Earlier in the season Father Gabriel Stokes burns his clerical collar, but in the end of this episode he is wearing it again. Especially doesn't make sense, because he said he gave up being a pastor.
Factual error: In the scene at the fire truck, Abraham uses the deck gun to kill walkers. However fire truck water pumps are powered by PTO from the engine, which isn't running.
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.
Revealing mistake: When Rick checks his revolver before holstering it, there are no primers in his cartridges.
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 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.
No Sanctuary - S5-E1
Revealing mistake: When Sam has his throat slit, the location of the wound does not correlate with where the blade was shown to be slicing the skin.
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.
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.
Revealing mistake: After it starts raining there is a shot looking at the road in The Distance. Notice how the rain is only falling in a small area and stops just beyond where the group is at. The road is dry from there on out.
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)
No Sanctuary - S5-E1
Character mistake: When Gareth is questioning Rick about what was in the bag he hid in the woods, Rick replies a .44. Rick is referring to his Python, which is a .38 or .357, not a .44.
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)
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)
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)
Other mistake: When Gabriel is out by himself on the road and kills two walkers, he is wearing a white shirt. Blood is shown spattering everywhere, but his shirt remains spotless. (00:37:00 - 00:39:00)
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