During any time that you can set a restart from the options menu (in game), you can use it to get to areas otherwise impossible to reach. Ollie then pause game play before you start coming down. Set a restart while in the air. Then, go to the restart, quickly Ollie again, then set the restart at the top of the Ollie again. By repeating this you will get higher and higher, and may be able to access rooftops and ledges (if you are close enough).