Ghostbusters Easter Eggs

If you look closely at the groceries in the scene where Bill Murray and Sigourney Weaver return to her kitchen, you can see that the bag of marshmellows behind the eggs are stay puft marshmellows with a picture of the stay puft man on the front.

Ivan Reitman (the director of ghostbusters 1 & 2) did the voice of Zuul, the crazy god with the flat top.