HIdden Surface Removal

Hello, I am making a game and am wondering how to fix a problem. In the game, the hidden surface removal seems to be turned off. Can anybody help me with this very frustrating problem?

select all objects and Control A to fix the bounding boxes.

if that doesn’t do it, look in the dynamic panel, and increase/reduce the radius.

I’m kind of new to Blender. Can you explain how to reduce the radius?