How do you make Inpenetratable Object
This i Tryd but with no succes http://blenderartists.org/forum/showthread.php?t=156455
The physics is calculated in “steps”.
If an object moves further then the length of itself in a single physics “step”, then that leaves a gap that allows the object to potentially pass through a point without registering a collision.
maybe you can increase the physics rate. cyborg dragon had the same problem with a golf game and solved it, but your framerate will go down.
or just increase the bounds