Dana Barrett was originally in the script, but Sigourney Weaver turned down the offer to play the role. However, Weaver changed her mind when the rest of the film's cast, including Bill Murray, were signed on, but by that time, Dana had been written out and the part had been rewritten as Dr. Ilyssa Selwyn (played by Alyssa Milano).
This game is considered by fans as the true Ghostbusters 3.
A monitor in Egon's lab displays, "Conglaturation!!! You have completed a great game. And prooved the justice of our culture. Now go and rest our heroes!" This is the endgame text from the original Ghostbusters video game for the Nintendo Entertainment System, typos and all.
This was never mentioned in the previous two movies, but according to the Prima Player's guide for the game, Winston Zeddemore used to be in the Marine Corps.
At one point in the game, if you check the voicemail machine upstairs you'll receive a message from a Professor Jones who inquires about the whereabouts of the Vigo painting, saying that it's priceless and that "It belongs in a museum". This is an obvious reference to the Indiana Jones movies.