Revealing mistake: When the ghosts are released from the storage unit, there's a shot of the light beam followed by a wide panoramic view of New York where the ghost lights depart as strings and orbs of energy. If you look at the Empire State Building, you can see that the first orb supposedly passes behind it, but its outline can be in fact seen through it. (01:09:05)
Factual error: When Dana first arrives at her apartment building, you can see a view of her getting ready to cross the street the front door from above, and the demon dog statue's head is in the shot, looking down. If that building is as high as they make it out to be, the distance between the dog, which is on the roof, and the street would be a lot more than it is in the shot. You probably wouldn't even be able to see Dana from that height. (00:16:50)
Continuity mistake: Louis/Vinz Clortho is dropped at Ghostbusters office at night at the same time Venkman is drugging Dana/Zuul at her apartment. When Venkman calls from her apartment it is night, Janine is in the same grey striped blouse, black skirt and tights outfit during that call she was wearing when Louis was dropped off by the police, at this time Venkman says he is on his way back to the office. Venkman does not arrive until the next morning, during the EPA raid, he is still wearing his same brown date night jacket and blue shirt but it's daylight now and Janine has changed into a new outfit, red blouse, grey vest, grey skirt and red tights and does not look like she slept at the office, Egon has also changed at least his tie and put on a suit jacket.
Continuity mistake: Trying to escape the demon dog, Tully trips over a chair and bangs against the windows of the restaurant. You can see in the first shot that the maitre d' (the guy with grey hair and stache, wearing black) is looking at him. But in the reverse shot, he's smiling at the patrons at the table, and only a moment later raises his head to check out what the fuss is about. (00:54:35)
Continuity mistake: When Vinz Clortho sprints off the building's front doors to chase Tully, the distance between the passers-by changes. (00:54:05)
Revealing mistake: Tully just ran away from the apartment building screaming. The doorman repeats to an incoming couple "A bear, in his apartment..." The husband pulls his wife back without for a single moment glancing at the direction the beast (or its growl) come from; he stares constantly at the foreground. (00:54:00)
Continuity mistake: Dealing with Tully, Annie Potts says one rather oddly foreshadowing line to Harold Ramis about his death, and then clings to him. Ramis puts a hand on her shoulder, and the position is different in the next shot. (01:02:00)
Continuity mistake: When Venkman is in Dana's bedroom the quantity and quality of light coming through the window changes between shots; look at the side of the window when he is counting down, for instance. (00:58:30)
Continuity mistake: During the scene with the possessed Dana in bed with Peter, the pillows rest at different heights against the bed's headboard. (00:57:30 - 00:58:40)
Continuity mistake: When Dana struggles with the literal arm-chair, one of the arms pops out of the top of the right armrest and a clawed hand clutches Sigourney Weaver's face. Change of camera angle, and not only she is struggling against the demonic limb in a different position, but the hole is gone from the top of the armrest, the arm is sticking from the side. (00:51:45)
Continuity mistake: The lighting in the scene with Venkman stalking Dana outside the concert hall is inconsistent. For instance, when he quips "I've got hundreds of people dying to abuse me", Dana's stiff friend leans against a fountain that is bathed in sunlight. Mere moments later the section of the square is in the shade. (00:43:10)
Continuity mistake: There's a crumpled piece of paper on the shelves behind Peter when he argues with Walter Peck in his office. As you can observe when Peck sits down, the paper is in a different position in the close-up compared to the wider angle. (00:47:40)
Continuity mistake: The famous Twinkie scene; notice that when Egon utters the line "Let's say this Twinkie represents the normal amount of psychokinetic energy" etc, there's a cut mid-sentence. Harold Ramis is holding the bar with 3 fingers in the first shots, 4 in the second. (00:48:05)
Continuity mistake: When Winston gets the job after the very tough and thorough interview process, he walks up to Ray. Between shots, the messy cables of the traps Ray is holding are in a completely different position, and he holds the paper sheet at a different height. (00:42:20)
Continuity mistake: When Peter gets slimed, the very marketable goo stains his uniform completely messing up the right half of his chest. In the ballroom scene the uniform is practically clean on that side, but got dirtier over the left shoulder.
Revealing mistake: In the shot that follows the one with the fake cover of The Atlantic, a bespectacled Asian man walks across the street, in front of the Ghostbusters, looking prolongedly straight at the camera. (00:40:20)
Factual error: The newspapers in the 'rise to success' montage have all the dates wrong; Usa Today says Tuesday October 8, 1984 (it was a Monday), New York Post says Thursday October 22 (it was a Monday). The USA Today also has a headline "Thin Man dies" which refers to William Powell's death, in March, and the Globe cites "Princess Di expecting again!", which was announced in February (but the fake mag is dated October). (Note; the USA Today details are in the left column and need you to pause, but the others don't - you can also find perfect reproductions of the prop online). (00:39:30)
Continuity mistake: When Ray Stantz slides the trap across the ballroom to catch Slimer, the cord is curled, but it is perfectly tense in close-up. (00:37:05)
Continuity mistake: When Venkman radios Ray to tell him about the ghost, look at the cart in the background when Ray answers; the mess does not look the way it looked in the earlier close-up; there's less stuff on the partially knocked down scaffold and the table ricocheted away from the wall but here the flowers are back on it. (00:33:20 - 00:33:45)
