Plot hole: Diana in her final scene is seen shooting her last bullets at the walkers that are offscreen, moving toward her, so suicide was not an option, meaning the walkers would have eaten her until she died, becoming a walker. And yet her body is completely clean when her son and Michone discover her in walker form. Blood free (even on her clothes) and fully intact, no chunks of her missing, no bite marks.
Chupacabra - S2-E5
Plot hole: How is it possible that Glenn did not see the missing Sophia in the barn full of walkers at the end?
Answer: No, she actually tries to talk Rick out of it, but he's already made up his mind, minutes later when Daryl asks him about the location of his brother Lori says "he'll show you."