Trivia: When Ray and Egon see Vigo's name on the "Occult Reference Net," his last name is the same as the twin actors who play Oscar.
Trivia: Slimer had no name in the first Ghostbusters movie, but the producers nicknamed him "onionhead" because of his awful smell. He was named Slimer in the cartoon series "The Real Ghostbusters." The name came from the scene in Ghostbusters where Ray shows Winston the containment unit and says, "This is where we store all the vapors and entities and slimers we trap." Since Venkman was slimed in the hotel, they decided to name the ghost that did it Slimer.
Trivia: Oscar is actually played by twins, Hank and Will Deutschendorf. These boys are the nephews of the late singer John Denver (formerly Deutschendorf). The boys are John's brother Ron's children. Tragically, Hank passed away in 2017, after a prolonged battle with schizoaffective disorder - a serious mental-health illness he had been struggling with for years.
Trivia: When the ghostbusters go to see the picture of Vigo in the museum, Ray becomes entranced by looking at the eyes. Winston asks him if he is OK. Look at what Winston is holding. It's some form of ghostbusting gadget made out of a potato masher.
Trivia: The first draft of the script involved Dana being kidnapped and taken to Scotland, where she'd discover an underground world of fairy-tale creatures, fairies, monsters and witches. The Ghostbusters would then have to travel to Scotland to save her. Dan Aykroyd has said that the script was simply "really too far out... too inaccessible."
Trivia: A great deal of the film was changed after poor test-screenings. In the original cut, there's a scene where Ray is possessed by Vigo earlier in the film and dangerously drives the Ecto-1 through the streets. Eugene Levy also appeared as Louis' cousin who helps the Ghostbusters get out of the hospital. There was a sub-plot of Louis trying to catch Slimer but being comically out-witted every time. Several scenes were substantially longer. And the entire climax was completely different.