interior universe?

i was at the third island on the north side of it where that observatory is on
that big hill, i had the cars float on water cheat and the perfect traction on
so i could jump with the down button, and if you get to the top of the hill you
can't really go any further because the hill gets to steep but since i had
the traction cheat on i could jump over the low part in the hill wich is on the
west side of it and when i did i was floating in the water on the other side of that
dam,so i drove around on the water going to the west until i got up on the shore
then i started to drive on the land and i fell through the ground and was in some kind
of interior universe but i was driving on water, its kind of hard to explain so try it
and see what you think cuz it could just be a glitch or somthing only it happens everytime
i do it.

good thing to point out, i did the same thing