During the chase scene, Ray is behind the wheel of Ecto-1. But in one shot when the car drives straight at the camera, he is visible in the passenger seat (and none of the other Ghostbusters are visible).
While Ray struggles to get the car started after the bird of Kildarby rips off the roof of the Ecto-1, as Winston says in despair "Get movin'!", his right arm is colored as Ray's arm.