Director: Ivan Reitman
Stars: Bill Murray, Dan Aykroyd, Sigourney Weaver
Plot: Three former parapsychology professors set up shop as a unique ghost removal service. Under the new snazzy business name of 'Ghostbusters', and living in the old firehouse building they work out of, they are called to rid New York City of paranormal phenomenon
Almost none of the scenes were filmed as scripted and, in fact, almost all of the scenes had at least one or two ad-libs. Most of Bill Murray's lines are ad-libs.
In the middle of the film's initial release, to keep interest going, Ivan Reitman had a trailer run, which was basically the commercial the Ghostbusters used in the movie, but with the 555 number replaced with a 1-800 number, allowing people to actually call in. They got a recorded message of Bill Murray and Dan Aykroyd saying something to the effect of "Hi. We're out catching ghosts right now." They got 1,000 calls per hour, 24 hours a day, for six weeks.
Harold Ramis really had no intention of starring in the film, only writing it. But he decided to star in this film as Dr. Egon Spengler after he felt he was the best person suited for the role.
Had Eddie Murphy accepted the role of Winston, the character was actually meant to appear in more of the film. He was to have joined the team much earlier, and it would have been he who was slimed at the hotel. When Murphy declined the role, the script was re-written to have Winston appear about half-way through the film.
(At around 10 mins) The part where the bookcase falls over and Venkman asks Ray "Has this ever happened to you before?" was not part of the original script. The bookcase actually fell over of its own accord (possibly from being disturbed by various crew members) and the subsequent lines were ad-libbed. It was decided to leave this material in as it added an extra element of mystery to the atmosphere as to whether it was a natural occurrence, or a malicious act on the part of the ghost for which the soon-to-be Ghostbusters were looking.
The "marshmallow" goo was actually shaving cream. More than 50 gallons was dumped on Walter Peck (William Atherton), almost knocking him to the ground.
As revealed in an interview with Mix Magazine Online the hit song 'Ghostbusters' was created 4:30 in the morning when after almost 2 long days of trying to create a song Ray Parker Jr. saw a commercial for a drain company that reminded him of a scene from the film. That commercial helped him coin the popular line "Who you gonna call?" The lively chorus shouting the words "Ghostbusters" through the song were made up of the only people Ray Parker Jr. could find quickly enough to help him meet his deadline: his young girlfriend and her friends. In an interview in 2015, he said it was his son that shouted 'Ghostbusters' which gave him the idea.
The role of Peter Venkman was originally written for John Belushi.
The schedule for getting the movie into theatres for its scheduled release date in summer 1984 was so tight, director Ivan Reitman said that the final print included incomplete special effects shots and errors like "wires showing" but, "remarkably, people didn't care".
After Harold Ramis passed away, fans of the movie paid tribute to him by visiting the New York City firehouse used in the exterior shots and created a makeshift memorial featuring Nestles Crunch Bars (in reference to Venkman giving Spengler a candy bar) and Twinkies (in reference to Spengler using the Twinkie to describe the ghost problem in New York City).
The original script had a budding romance between the cynical receptionist Janine and the blissfully out of it Egon, but most of it was edited out of the film. The relationship between Janine and Egon was explored more in the animated series that followed: The Real Ghostbusters (1986).
Dan Aykroyd's original title for the film was "Ghost Smashers".
When interviewing Alice the Librarian, Peter at one point asks her if she is currently menstruating, to which the shocked head librarian asks "What does that have to do with anything?" (and Peter famously replies "Back off, man. I'm a scientist."). From both a psychological and parapsychological standpoint, it's a valid question: in parapsychology there is some correlation between menstrual cycles and latent telekinetic powers, and from the psychology side, Alice, an older woman, may have been going through menopause, which in very rare cases causes psychotic breaks or blackout periods. In context, Peter was determining if Alice might have actually caused the disturbance herself, either physically or through psychic powers.
Louis, the future "Keymaster," gets locked out on three separate occasions.
During the Ghostbusters "Rise to Fame" scene and the news articles and publicities are rolling in, one of the front page newspapers shows a headliner above the main story proclaiming "Princess Di Expecting Again". In 1983, around the same time filming was underway, Princess Diana was confirmed to be pregnant with her second child. And in 1984, the same year the film was released, Diana gave birth to her second son, Prince Harry on September 15
Just before the team enters Dana's wrecked apartment, in the corridor outside can be seen, amongst other items, a tricycle very similar to that ridden by Danny in another classic ghost film, The Shining (1980)