Definitely a solid episode. The three best things about the episode are:
1. No Carl for a whole freaking episode. Now if they will just kill him off I will be a happy man.
2. Killed off Rusty Griswold really quick. He was going to be nothing but trouble.
3. They had an episode that had zombies in it, lots and lots of them.
Rick should have considered more options before doing the zombie marathon. Wouldn't the best thing to do be to grab some dynamite and blow up the roads into and out of the quarry? If you blow a huge hole in the road then the zombies can't escape. I am sure they had some dynamite with the construction site and the quarry both likely using it.
So who do you all think was blowing the horn? I think the list of suspects are:
Morgan - He just doesn't seem to like the new Rick. I don't know what good it would do for him to blow the horn, but he definitely looked like he had something on his mind when Rick sent him away. Plus who is his friend that taught him the bo staff skills after the apocalypse? Could he now be tied into the Wolves or another group? He also seemed mad about the peanut butter bar being stolen. I don't recall if he saw Michonne take it or not, but if he did, he might be upset about her lying. He was crazy for a while so you never know what might set him off.
Ron - While his dad was a dick, he was still his dad and he might just be pissed about it and not thinking straight. Plus he heard Rick and Deanna say not to bury his dad in town and basically just take him out and throw him on the ground and not bury him.
Deanna - She is probably mentally unstable to the point of doing something irrational. Maybe she figures to hell with everyone else if she can't be with her husband anymore.
The Wolves - I think a lot of people probably think it is them, but what would they gain by having the town get overrun by zombies? I would think you would want to take the town intact. If not, it would be hard to get the resources (food and weapons) and likely women. Those three things would be hot commodities in a zombie apocalypse in my opinion. They would be hard to get with 1,000 zombies running around.
Other - Enid (the girl that was sneaking out of the town) I think she is the one that took the gun that Rick hid outside of town. Is she sneaking out to meet with another group, possibly the Wolves? Maybe a new character that no one knows about yet?
I am torn on who I think it is. I am leaning toward Enid. If she is with the Wolves, then this likely is a distraction to maybe sneak some of them into the town while most of the people in and outside of the town are busy dealing with the zombies.