Rob Bricken at IO9 writes, "When it hit the ground, I literally said aloud "Please let the zombies follow them," and then, from inside the van there was the wonderful sound of the first zombie hitting the roof, followed by a dozen more. It was awesome, it was funny, it was creepy, and it was perfectly staged."
Weeeeee!
Behind the Scenes -
The cast and crew of The Walking Dead describe how the van scene was created. - This one has the sound of the walkers falling on the van after the drop.