Although the script has the scene taking place around Louis' desk, it was actually filmed in the upstairs rec area near the pool table. The black and white images came from a workprint video that was uploaded by William Forsche to Facebook and YouTube.
INT. FIREHOUSE - DAY
Louis is lurking behind a pillar, peeking out at the office area. We PAN DOWN TO the floor and see a foot pedal, then PAN ALONG the cord TO a ghost trap sitting on Louis's desk. Hanging from strings over the desk are several pieces of Kentucky fried chicken.
Slimer partially emerges and furtively sniffs the air, then spots the chicken bait. He licks his lips, materializes completely and flies to the chicken.
His eyes light up and he stomps the foot pedal.
The trap pops open and shoots out a powerful cone of energy. Slimer dodges it and escapes as a big section of the ceiling comes crashing down on Louis's desk.
(seeing the damage)
He slinks off, defeated.