Continuity mistake: When they arrive at the concert and are taken downstairs, the guy is explaining about Fernando. If you look at the high voltage strap she is wearing the writing changes to right way up to upside down then back again between shots.
Continuity mistake: An early shot of the Chinese Restaurant shows an open garage and the white bonnet of the new Ecto-1, despite the fact the Ecto-1 had yet to be introduced into the movie at that point.
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.