Continuity mistake: The Ghostbusters pick up the 'symbol' for their fight by looking at the license plate of their Ecto 1A, which sports in close-up the Statue of Liberty right between the O and the 1. Problem is, in the rest of the movie, and that includes just a few shots before when they were blasting the jelly shell with their protons, Lady Liberty is to the left of the plate, before the E. (01:26:15)
Continuity mistake: When the statue starts to walk it has irons and cables attached to the sole of its sandals. When it's walking downtown the shoe is clean and like new (most likely the first miniature has been replaced by a human in disguise). (01:28:20 - 01:30:15)
Continuity mistake: When Lady Liberty shows up on the streets, she makes a left turn towards a big avenue. From the ground shot the police cars and motorcycles have moved ahead and the road is clear. From the aerial angle the cars and motorcycles are right next to the statue's feet. (01:29:35)
Continuity mistake: The first shot of Lady liberty walking down the streets and looking down at people is an obvious human face in disguise and makeup. In the close-up shot, it is a mask/miniature that doesn't look like the previous one, but does resemble the real Lady Liberty. This is not due to the statue being animated by ghosts, for the mistake takes place between one shot and another (besides, the statue is animated all the time), but because the FX was achieved combining a human in disguise and a miniature set. (01:29:50)
Revealing mistake: When Lady Liberty walks down the street, the four Ghostbusters inside its crown are replaced with very obvious dolls. (01:30:05)
Continuity mistake: While the Statue of Liberty walks down the street, the shoe swaps from a blatant rubber sneaker with the welded planks painted on it, to a more-realistic shoe with real layered planks. (01:30:15)
Other mistake: When the Ghostbusters are inside Lady Liberty, you can see from their close-ups and from shots inside the head that the windows that form the crown are narrower than their shoulders. Despite that, they easily make the drop on the villains from there, while carrying huge backpacks (the slime ones have large tanks even). (01:30:20)
Continuity mistake: When the five men are inside the statue, the light on the background is green. Before they smash the museum there's a huge pink cloud that colours the statue pink on the wide angle. However in the close-up of the men the light is green as before. (01:31:35)
Revealing mistake: When the Statue of Liberty is about to smash the museum's glass dome, the shot outside is really bizarre: The Statue is standing on a park, with a pink cloud covering what is supposed to be the museum. Yet the lower part of the cloud plus the people around it, show that there is no building nor any foundations there: Just a superimposed pink cloud over an empty field. (01:31:35)
Continuity mistake: When Peter tells Ray to hose Lucasz, Dan Aykroyd's hand is below and then above the slime gun in the two separate shots. (01:32:15)
Continuity mistake: Before Dana is trapped by the rubber hose, the white tube it comes out of is on her left several meters away. A split second later, the angle changes and without her having moved, the white tube is by her right side a couple inches away. (01:33:00)
Continuity mistake: When Vigo throws the streams from the proton packs back onto the Ghostbusters, there is a wide shot of Egon getting thrown way over to the right. However, when they do a closer shot, he is way over to the left, closer to the other three Ghostbusters. (01:33:50)
Revealing mistake: When Vigo repels the Ghostbusters after they shot him, the lads bounce against the background...that bounces back against them, despite being 'solid concrete'. (01:34:10)
Visible crew/equipment: Vigo just knocked down the heroes who are looking at him powerless. Vigo then makes a gesture and parts the crates behind which Peter hid Oscar. As he does that gesture you can spot in the background on the left (mostly in the darkness) someone's arm doing the same (the movement is not exactly the same so it's not a mirror). (01:34:35)
Continuity mistake: In the museum, when Dana is trapped and the Ghostbusters lay on the floor, right before Vigo grabs the baby, Vigo's hair is fluffy and messed up. A shot later it's straight and neatly brushed. (01:34:40)
Continuity mistake: When Peter crawling like a worm draws the attention of the scourge of Carpathia that is holding the baby, shouting "Not so fast, Vigo!", notice Vigo's hair moving from the back of the right shoulder to the front. The hair changes position going in front of both shoulders to various° in the rest of the conversation. (01:34:55)
Continuity mistake: Near the end, the Ghostbusters make the Statue of Liberty smash the window on the roof of the art museum before abseiling in. The window gets completely destroyed, but just after Vigo says 'Now we become one' we see the window again and it appears less damaged than before. (01:35:50)
Revealing mistake: When Vigo drops the baby in the end of the movie, you can see it is a doll. (01:36:20)
Continuity mistake: When the Ghostbusters are getting up after being paralyzed by Vigo, you can see Ray in the background standing almost straight up, then there is a close shot of him still struggling to get onto his feet. (01:36:25)
Continuity mistake: In the end when Tully is shooting from the proton pack against the building that is covered in "slime" you see a wide shot of the building but you can't see Tully shooting anywhere. (01:37:30)
Answer: Because she knew Peter would want to get involved. They didn't part on good terms and she hadn't spoken to him since her marriage. She just thought it would be awkward to see him again.
Bishop73