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.
Continuity mistake: After the part where Merle and Daryl save the people on The Bridge, Merle gets agitated at Daryl and grabs him and rips his shirt. On the left side of Daryl's back, he has tattoos on his right side, but as he walks away he suddenly has the tattoos on his left side. (00:25:50)
Continuity mistake: In the scene where Merle is the in big box late 80's chevy with big 20-22 inch rims he is shown driving it in the barn yard drinking, playing music, and zombies following him. The shot changes a few times within the same scene with the big rims on, in one shot the car is shown with him driving it but the stock rims (15") are on the car, the paint of the car looks a little darker too. Then the shot changes again while he is still driving it and the big rims are on the chevy again. The shot that shows the stock rims is a pretty fast shot so it could be easy to miss.
Revealing mistake: Merle is sitting in a chair and talking with Michonne and Andrea. At one point he takes off the prosthetic on his right arm to show them what used to be his hand (it's only a nub now), but shortly afterwards you can see his right hand in a fist as he puts the prosthetic back on. (00:13:00)
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)
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)
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.
Other mistake: In Woodbury, on the street, while Andrea talks to the Governor, we can see everybody wearing jackets and orange, red and yellow trees, showing that the scene was shot during fall. According to the beginning of the third season, they had just passed through a hard winter. So it should be spring or the beginning of summer.
Revealing mistake: After Andrea avoids the truck on the road, she is attacked in the woods by some walkers and pinned to a tree. After breaking free, she goes to stab a woman on the ground with her knife. But as she goes to strike, you can see the actress slowing her strike down "pulling the punch" and gently resting the blade on the walker's head instead of actually striking. (00:20:41)
Continuity mistake: When Rick, Carl, and Michonne are leaving King County (Rick's home), they must travel around a wreck involving two cars and an overturned RV. They drive along one side of the road. When the camera angle changes, they are on the opposite side of the road. (00:41:30)
Continuity mistake: The previous episode ended with Rick and his group reaching Woodburry and it was dark. This episode starts with Tyreese and his group reaching the prison in the daylight, and being rescued by Carl and brought back to their cell block. If you look at the windows it is still light out, they have no electricity so it can't be exterior lighting, yet in the scene before and after this, Rick and his group are at the Woodburry at nighttime.
Continuity mistake: When helping the foreign family to fight off the walkers, Daryl pulls the zombie back into the car and slams its head in the boot door, covering his hands in blood in the process. However, for the rest of the scenes in the episode and in shots directly afterwards, his hands appear totally clean without him doing anything to clean them. (00:22:00)
Continuity mistake: In the final scene of the episode, Rick and Hershel are talking while looking out over the prison yard. Near the end of the conversation, Rick squarely faces Hershel and says "I'm hoping you could talk me out of it." The camera then changes to Hershel, and Rick is now immediately facing 90° to his left looking over the yard. When the camera changes back to Rick, he is now looking directly at Hershel.
Visible crew/equipment: Governor is 'interrogating' Michonne privately about staying at Woodbury to "join his forces." As he mentions Merle's name, she suddenly reacts, grabbing her sword from him, and shoves it at his throat, threateningly. During this, the shadow from the boom mic is visible just above his head. (00:13:50)
Continuity mistake: When the Governor first attacks the prison, he is standing on the driver's side but in front of the truck. Next, Michonne aims at the truck and now the black guy who was always with Martinez is shot dead on the driver's side. Then after that, you see he's alive again on the passenger side right before the other truck comes crashing through the gates with all the walkers inside.