Revealing mistake: Towards the end, when the ground is shaking and breaking up, a police car falls halfway into a hole in the road. When the smoke clears a little you can clearly see two white poles, one on either side of the back left wheel, holding the car in place. (01:21:04)
Revealing mistake: In the earthquake scene where the road is cracked, you can see the cloth on the side of one of the cracks flapping in the wind. (01:20:35)
Revealing mistake: In the ballroom scene, when Slimer is flying around the chandelier, he disappears for a few frames when he reaches the far side. [This animation is mentioned in the DVD commentary. The film makers were generally unhappy with the entire animation and the fact that the representation of the apparition did not resemble those previous and that the movement was very unconvincing.] (00:35:05)
Revealing mistake: When the police car falls into the hole, if you watch the ground that's rising up in front of it, when it finally comes to a stop, you can see how light it is because it bounces, and you can tell that the pieces of the pavement are moved by hydraulics. (01:17:45)
Revealing mistake: Near the end of the film when the Ghostbusters take cover in a small corner and come up with the "cross the streams" plan, look closely at Peter's proton pack, you can see that it is a foam "stunt" pack as there is a small sticking out part that keeps squashing against the wall behind him. (01:32:25)
Revealing mistake: When the Stay-Puft Marshmallow Man is walking through the city, in several shots you can see outlines of people and buildings through the marshmallow man, who was added in optically. (01:32:05)
Revealing mistake: A shot from above Dana Barret's apartment, from just above a statue looking down on the road below: The statue in the foreground is partially transparent. We can see the double yellow line on the street go straight through one of the statue's upper fangs, and one of the white lane dividers going through the statue's lower jaw. Viewed on Bluray disc. (00:16:50)
Revealing mistake: As Dana's apartment crumbles apart to present the temple of Gozer, there is a tight shot of a gargoyle falling off an exterior corner. Carefully lined up with features on the gargoyle's face - but still readily visible - are the black strings that pull the gargoyle face off its mount.