Zombies running through the walls, objects inside buildings, stairs.
Light from flashlights shines through the walls of the buildings and is visible from outside (and no, not through the windows, but solid walls).
Sound of consuming food and drinks is super loud allowing other people to hear it from long distance - up to 50 meters (estimate based on the distances from building to building).
Sounds of forest and ocean are way too loud and make it almost impossible to hear anything else while in the area.
Climbing ladders/stairs only to randomly fall off.