Once Shane tackles Jim, pinning him down after he is digging holes, Jim expresses what had happened to his wife and sons. In this shot, we see him pinned down to the ground, his hat knocked off. But in the next shot, Jim's hat is back on his head.
It is often said that the presence of manholes in the alley where Glenn is taken by the Vatos is an error. On their previous trip to Atlanta, Glenn was asked to look in the alley and see if there were manholes and he said no but this is not the same alley. When Glenn helped Rick out of the tank and they climbed the ladder to the roof, they went across a bridge and down into a different building.
The shotgun Rick has while confronting the Vatos is not a fake, it's a Mossberg 500 Persuader, a shotgun commonly used by law enforcement. It does in fact have a trigger, Rick's finger can be seen resting on it, though it is hard to see due to the fact that the trigger rests almost all the way back against the trigger guard when cocked, this is one of the reasons it is favored by law enforcement because it has a hair trigger.
In several close-up scenes of Daryl with the crossbow, you can clearly see that it's not loaded correctly. The nock of the bolt (arrow) is resting well above the bow string and no way would it fire properly.
Part of Rick's reason to return to Atlanta, besides looking for Merl, is to retrieve his bag of guns. In fact they almost have a shoot out with the other group over the bag of guns. Yet, throughout the downtown dozens of machine guns and holstered pistols can be seen on dead soldiers and several M-60s can be seen sticking up from the sandbags.
The fishing poles Andrea and Amy are using are fly fishing poles, they are not designed to be used for bottom fishing the way they were.
When Glenn is being kidnapped in the alley & dragged to the car, during the struggle his shirt is lifted up, revealing the lav mic taped to his chest.