Dennis Schroder's Wednesday night went from awesome to pretty crappy real quick ... 'cause just after the Lakers point guard helped his team beat the Spurs -- a vehicle he was riding in was stopped by cops in Hollywood.
Cops tell TMZ Sports ... it all went down at around midnight, just a couple hours after the Lakers game had ended. According to an LAPD spokesperson, the stop was initiated after the vehicle allegedly had improper plates.
Video from the scene shows cops spoke with Schroder and what appeared to be his driver for about half an hour after pulling over the ride at a gas station.