Monaco is a land where the amount of money you have and the car you own is directly correlated to the amount of laws you need to obey. If you are willing to put a Gallardo Super Trofeo car on the street, apparently you can.
This Gallardo is obviously not road legal. Sure, it now has road tires affixed to it, but there is no way it could be properly registered. Hell, our own Máté points out that in the course of this video, there is a duct taped German plate on the car and a Swiss plate on the back.
And the police probably just let it go because they don't want to deal with all of the red tape. Or because they'd rather keep big money coming into the principality and spend their time trying to keep out the riff raff.
Hat Tip to Thomas!