Thriller Zombies...

In the music video for Michael Jackson's "Thriller", there are several zombie's that climb out of their graves and dance, yes? And they are all relatively fresh corpses, so how is it that they all came out of this one tiny, overgrown, ancient-looking cemetery?  

Yes, I recognize that this is a music video and it doesn't have to be accurate, as accurate as one can be when it comes to zombies. (I think you can be very accurate about zombies, so don't even get me started.) Anyway, surely there are some people out there with interesting solutions to this problem, just for fun.