I've found so many I just stopped paying attention to it. Just watch the first episode of this season where they're taking over the prison and they show close-ups of them shooting: the slides on the handguns aren't moving, the cylinders on the revolvers aren't indexing, and nothing on the rifles are moving (not to mention they rarely seem to have any recoil). There's also last season when Hershel is defending the farm and shoots over 20 shots with his shotgun without reloading... or the Soviet DShK in season 1 that was set up to defend the CDC in Atlanta..
But then you get into the other details, such as the National Guard members having to load (you did see him pull back the charging handle to chamber a round, right?) as the Governor was driving up. Some of the guys didn't even have magazines in their rifles. Then you wonder why, after 10 months or more of being in a zombie-infested world, they didn't have enough situational awareness to notice the Governor's men "sneaking" up on them, and just stood there and got shot during the ambush. Then you had Rambo with no shirt on just hanging out.. You could assume they might not be infantry and might be cooks, drivers or something else, so I wouldn't expect them to set up any kind of formation like a wagon wheel, but come on.. they had a fenced-in gate that was wide open and nothing on the sides.
Anyway, as much as it annoys me I really love the show. It's actually the only one I can get into and refuse to miss.. I even changed my work hours so I can be home for at least the 10pm showing, if not the 9pm showing.