The Glowing Green Glob fly above the Ecto-1A in Scene 2: Hitting the Road and Scene 4: Ghosts in the Park of Ghostbusters II Video Game. Not to be confused with the enemy Glowing Pink Glob in Scene 4.
It floats above and is pop-able. Depending on which glob is popped, a color coin will then fall and bounce on the street til its off screen. Collecting the coin will give you a upgrade.