Walk with Me - S3-E3
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)
Walk with Me - S3-E3
Character mistake: When Andrea asks the Governor his real name, a young girl in pink shirt is walking like a "walker" and abruptly shifts to normal gait.
Suggested correction: She was never walking like a "walker." She was wondering around like many of the other extras. She looks like she was waiting for her family and when the boys approach, she stops wondering around and walks towards wherever they live.
Say the Word - S3-E5
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)
When the Dead Come Knocking - S3-E7
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)
When the Dead Come Knocking - S3-E7
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.
When the Dead Come Knocking - S3-E7
Continuity mistake: The Governor takes off his gun belt while interrogating Maggie, and a few shots later has it on again in the same scene.
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.
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: 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: 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: 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.
Suggested correction: The man you're taking about is Shumpert aka "Bowman." He's was not shot dead. He dove for cover and is still alive. In fact, he's in at least a half dozen more episodes, including in season 4.
Continuity mistake: When Rick, Michonne, and Carl go out on a run, in the first shot, Rick starts to roll the window down so he can shoot a walker. The next shot the window is up, and he rolls it down again. (00:02:00)
Continuity mistake: When Carl shoots the masked man who is found to be wearing body armor, Rick pulls up the armor to find the bruised ribs of a Caucasian male. When the assailant is unmasked however we see that the Caucasian male has magically transformed into an African American man. (00:11:20)
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 going the other way. (00:41:30)
Arrow on the Doorpost - S3-E13
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.
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)
Revealing mistake: When the Governor is hunting Andrea, he smashes a few windows in the building where she's hiding. When he breaks the first two, there's a jet of steam or air, showing that it was broken a split second before he hit it with the shovel. (00:29:04)