King Kong Easter Egg - Water Slide

On the level "Jimmy" you start by walking down a path. You start with a shotgun but grab the rifle from the box up the path. When you hear carl say "Kong... King Kong" and start filming the mountain, zoom onto where he is filming and you will see a small doorway with what appears to be a water slide going down the side of the mountain. It looks to small to be the stairway to kongs lair