Factual error: In the scene where 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 Darryl waiting outside the room. You hear the gun go off and then you hear a shell casing hit the floor (noticeably "lighter" than the sound the revolver would make when dropped). Revolvers do not eject a shell casing.
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.
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.
Visible crew/equipment: During the scene where Daryl's group finds the auto shop, Daryl spits on his hand to wipe the window and is surprised by a zombie banging up against the window. He says, "Got some friends inside" and walks away. The camera pans to the window and a crew member wearing a white hat and (what appears to be) an orange shirt is visible in the reflection. He seems to be taking a picture (probably for continuity, which is pretty ironic).
Continuity mistake: Glenn demands that Abraham stop the truck so he and Tara can get off, the two male characters then have a scuffle. We can see Eugene in the background standing next to the truck facing right of the camera. But when the camera cuts back to Eugene by himself, he's now facing the opposite direction. Also the items in the back of the truck move from left to right.
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.
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: Right at the end of this episode when there is another flashback to the prison, the baby is seen many times. Judith is asleep, then the camera angle changes and she is awake, it moves back to another angle and she is sleeping again. This is repeated several times.
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.
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: After The Governor shows up at the prison with his arsenal, Hershel and Michonne are taken out of the vehicles and placed kneeling on the grass side by side, about 1 arm's length apart from each other. But when Rick makes his way down to the fence to talk with The Governor, Hershel and Michonne are now about 4 arms' lengths away from each other. This goes back and forth for a few shots.