Does Angry Bots demo have invisible Colliders??

Hi!

Im triyng to learn the best technique for making collisions on floors in my little game, so I decided to search it in the demo that comes with Unity.

I selected different chunks of the floors and any one has a collision component! The same with half of the walls and objects on the entire level! How the player can collide with them?

,They have added colliders on empty game objects, you can find them under environment(static)/colliders