Plainclothes officers in an unmarked car stopped the star rapper, whose real name is Curtis Jackson, at about 2 p.m. after he allegedly made an unsafe lane change.
As a crowd gathered and snapped photos with cell phones, the officers ordered 50 Cent out of the flashy sports car and took him to a nearby station.
The rapper was cited for a lane-change violation, and for having an expired license and no registration, said Detective Christopher Filippazzo, a police spokesman.
He was let go after a friend showed up with proof that 50 Cent owned the vehicle. The friend, who had a valid license, drove him away, police said.
A call to 50 Cent's music label, Interscope Records, was not immediately returned.