Trivia: The "Demonic Balloons" that attack the Ghostbusters are almost direct re-creations of real Macy's Thanksgiving Day Parade balloons from the 1930's. The filmmakers decided to use the real designs in order to represent the "spirits" of New York's history... and also because they were quite eerie and unsettling.
Trivia: In order to enhance the 3D effects in the film, some elements like slime and the proton beams are rendered to go "beyond the borders" and into the black matting that is present at the top and bottom of the image. This effect is also maintained in some 2D home-video releases of the film.
Trivia: Even though this film isn't connected to the original films, Harold Ramis, Bill Murray, Dan Akroyd, Annie Potts, Ernie Hudson and Sigourney Weaver all make cameos in this film. Harold Ramis as a bust in the hall of the university where Erin was going to teach; Bill Murray as supernatural debunker Dr. Martin Heiss who dies after Mayhem kicks him out the window; Dan Aykroyd as a cab driver; Annie Potts as the snooty hotel receptionist; Ernie Hudson as Patty's uncle who gave her the hearse to drive; Sigourney Weaver as Holtzman's mentor Rebecca Gorin.
Trivia: The casting of Leslie Jones as a subway employee Patty caused some controversy as the only non-scientist character in the film was being portrayed by an African American actress. In actuality, the part was originally intended for Melissa McCarthy while Jones would have played McCarthy's role. Jones and director Paul Feig both secretly wanted Jones to play Patty (as they felt it was too similar to McCarthy's prior roles, and they wanted to "unleash [Jones] onto the public" like McCarthy had been in Feig's prior film "Spy"), so they swapped her role with McCarthy's, despite knowing it might cause some controversy.
Trivia: Erin says "Mercado" is Spanish for "table" when it is actually Spanish for "market." "Mesa" is in fact Spanish for "table." It's a running gag that Erin is really bad at Spanish. Earlier in the movie, she mistranslates what the theatre janitor was saying when he went past on a gurney.