Continuity mistake: On the roof all the survivors are discussing their escape plan while T-Dog is lying down injured by Merle. In the next scene people are wearing rain coats and covering their bodies with the walker's remains as Rick proposed. T-Dog has taken off his cap and looks fine. Rick gives him the handcuff keys to free Merle. In the scene after, while Rick and Glenn went out the streets, the others go back on the roof to watch them from above. Nobody is wearing a raincoat and also T-Dog is in the same condition as before, lying down with his cap on. (00:24:00 - 00:31:15)
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: When the car flips in the chase scene, you can see the round canister used to flip it. (00:10:25)
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)
Other mistake: In the opening scene when the cop stops at the side of the road & walks between the truck & car you can see there is no engine or transmission on the truck lying on its side. (00:00:20)
Audio problem: In the scene when Andrea is mourning the death of her sister, Rick walks up to "tell her how it is." Andrea points a gun at Rick with just her right hand. When the gun is coming up to Rick we hear the slide being cocked, this can only be done with two hands. (00:03:35)
Revealing mistake: Near the end of the show, while Rick is still in Atlanta (he is on a secondary paced road), you can see vehicular traffic moving on a bridge in the background.
Continuity mistake: The stinger is deployed and is seen. Camera changes into the car and the stinger has vanished from the road. (00:09:20)
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.
Continuity mistake: After they steal the car with the alarm blaring, there is a shot of the white van turning left down a road. It has just rained but the road is bone dry. A shot later there is water on the road.
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)
Continuity mistake: As the scene opens on the rooftop with Daryl, T-Dog, Rick, and Glenn observing the area that Merle had been handcuffed to the pipe, blood splatter magically appears around the severed hand when it wasn't there at the end of the previous episode. (00:05:10)
Visible crew/equipment: When Rick hugs his family, a crew member can be seen filming over the red car. (00:10:40)