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)
