Isaac reveals that Roland will invent a "Ghost Bomb" in the future. However, Egon already built a device of the same name in The Boogieman Cometh (1986).
Like in Ghostbusters (1984), Egon uses junk food to illustrate their problem. Here he uses a jelly doughnut whereas in the movie, he used a Twinkie.
This story takes place on July 30th. The future Tempus points out the date in Times Square.