Also, the music couldn't have been THAT loud, since the group was talking to eachother in normal voices right next to the radio.
Good point. It was meant to pull the zombies right there to the fence, not to bring in hordes from everywhere else.Also, as commented on above, the zombies didn't hear the bottle, the heard the shelving untis falling down and the dozens of bottles. They also showed water leaking in, so that part of the roof was already compromised and not that hard to hear through.
Oh well, I liked that scene. The funny part is that of all the complaints, I am still surprised that the helicopter wasn't one of them. I would have thought a helicopter that big crashing like that would have damaged the roof far more than it did. The blades would have broken and really damaged the roof even without the impact of the helicopter going down.