Factual error: When Rick has given Andrea his revolver to end her life, he leaves the room with the others to leave Andrea and Michonne alone. The next thing you see is Rick, Tyrese and Daryl waiting outside the room. You hear the gun go off and then you hear a tinkle as a shell casing hits the floor (noticeably "lighter" than the sound the revolver would make when dropped). Revolvers do not eject a shell casing.
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.
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.
Factual error: The grenade Rick finds in the tank has an unpainted body and a blue safety lever. It's a dummy training grenade. (00:06:20)
Factual error: One of the machine guns set up to defend the CDC in Atlanta is a Soviet DShK machine gun. This weapon would not be in use by American troops in an American city.
Factual error: Season 5 and they are still driving cars around! Gasoline won't last years unless specially treated.
Factual error: In the opening scene and throughout, young Sam Anderson, cloistered in his bedroom, is presumably listening to a crackly 45 rpm copy of Nick Lucas crooning his 1929 hit, Tiptoe Through the Tulips. In reality, the disc with gold/blue label spinning on Sam's turntable is not the song playing. The original Tiptoe was released in 1929 on 78 rpm vinyl by Brunswick Records, and was finally pressed on vinyl 45 by Accent Records in 1974 (solid robin egg blue label however, not gold/blue).
Too Far Gone - S4-E8
Factual error: When Lilly comes across the Governor's body, she points her 1911 at him. In one shot, we see her from behind with the hammer forward on her 1911. In the next shot she immediately kills the Governor by shooting him. A 1911 will not fire unless the hammer is back. (00:49:00 - 00:50:00)
Factual error: At CDC headquarters, Dr. Jenner shows Rick and the group an MRI of an infected patient's brain activity as they die and subsequently resurrect. The patient is shot at point-blank range as the barrel of the gun can be seen in the MRI. This is impossible. MRI machines are highly magnetic and the gun would have been ripped from Dr. Jenner's hands with such force that not only would he not have been able to shoot, the MRI machine would have been destroyed.
Factual error: The microscope in the CDC lacks objective lenses. (00:36:27)
Factual error: Rosita picks up a spent cartridge fired from the desert eagle earlier in the episode, which is either a .357 Magnum, .44 Magnum, or .50 AE as those are the only chambers that the desert eagle is made in. She then asks Eugene to make her a bullet. In the following episode he does and she uses that bullet to fire a pot shot at Negan. But the casing that she picked up would not fit the 9mm Beretta she uses, nor could it be modified to do so.
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