Continuity mistake: At about the middle of the film, when the Ghostbusters are rising to fame and are appearing on the front of newspapers and magazines, the photograph on the front of the New York Post is taken from the end of the film, just before the four of them cross the streams from their proton packs. (00:39:37)
Continuity mistake: When the eggs pop out of her bag and start cooking on the counter, they're in different positions depending on whether it's a close up or wide shot. (00:18:55)
Continuity mistake: When Winston gets hired, Venkman and Stantz have just come back from a job. They're covered in slime and Venkman's smoking. Ray gives Winston an armful of traps. We then cut to Venkman chatting to Dana after a rehearsal, so we assume it's later, maybe even a different day. After that scene though, we then cut back to Stantz showing Winston (wearing the same shirt) what to do with the traps, and Venkman talking to the guy from the EPA. Venkman's got the same slime pattern on his shoulder, and is still smoking. Looks like the Dana/Venkman scene was in the wrong place. (00:42:00)
Continuity mistake: When the hotel manager refuses to pay the bill after the Ghostbusters capture the green ghost (Slimer), you can see he is putting his handkerchief into his top pocket with his left hand, but in the very next shot he can be seen putting the handkerchief in the pocket with both hands.
Continuity mistake: The large blue book that Peter drops on the table to startle Egon disappears off the table in the next shot. (00:07:10)
Continuity mistake: At one point in the movie we see the end of the hallway in Dana's apartment and the end is of a window and the wall around it is red like the end near Dana's door. However, (either when the Ghostbusters arrive at the end or when Louis is being attacked by the terror-hound) the whole hallway (even the other end) is all white. (00:17:15 - 00:53:30)
Continuity mistake: When the mayor orders Walter Peck out of his office, you can see that he is pointing his finger at Peck, but when the camera angle changes his hand is nowhere to be seen.