Continuity mistake: When the guys blast the glass lamp in the hotel, it falls on a table and messes up the table and chairs around. In the following angle the chairs are in a different position and the area, which was dark half a second ago is now perfectly lit, without anyone having moved and, most important of all, after the big lamp has been shred to pieces.
Continuity mistake: At the Lincoln Center (that place Dana's orchestra plays at) the nerd with her has his case and they're leaving when Peter is there. Nerd-boy goes off to the side and waits. When they start off again, his case pops back and forth unhumanly between being carried under his arm and in his hand between long and close shots about 3 times. (00:44:34)
Continuity mistake: When Dr. Venkman is looking in Dana's refrigerator the items on the top shelf shift position, disappear and/or are replaced with other items. The large glass dish that was on the left of the Coke can is replaced by a small plate of food. The Coke can turns. There is also now a large bottle behind the Coke can. Clearly these 2 connected shots were filmed on different days and the items were stocked without regard for the previous shots items and positions.
Continuity mistake: When the 'disgusting blob' goes through the wall above the vase of ferns after being attacked by Ray, you can see two small amounts of slime appear on the wall. In the next scene, when the food trolley crashes into the table, there is more slime on the wall than there was in the previous shot.
Continuity mistake: Venkman meets Dana by a fountain. When he says goodbye to her, first a man with a hat passes behind him and disappears in the next angle; then, in a close-up, Venkman is surrounded by dozens of people who vanish half a second later in the wide angle, where the place appears empty.
Continuity mistake: When Egon tries to prevent Walter Peck from shutting down the protection grid, he has Janine and Vinz (Louis) behind him. You can see that Vinz is raising his right arm, but in the next shot his right arm is now lowered down.
Continuity mistake: When Dr. Venkman investigates Dana's refrigerator, there is a Corning dish and a can of Coke side-by-side on the top shelf. The camera cuts twice, and there is suddenly another item (looks like lunch meat) that appears in front of the Corning dish and the Coke can.
Continuity mistake: In the scene where the earthquake begins, the Ghostbusters fall into a hole. They're in two rows - in the first row are Venkman and Ray and in the second row are Egon and Winston. In the following shot, it is now Ray and Winston on the first row and Venkman and Egon on the back row. (01:20:30)