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.
Over My Head - S3-E4
Plot hole: Daphne was able to hurt Duke because his name appears on her cell when he called, but names only show up on a cell phone if the person's number and name are programed into the phone, and Duke has already said he doesn't know her.