Although Harold Ramis could not make a cameo like his costars from the original Ghostbusters due to his death in 2014, you can see a bust of Harold just outside of Erin's university office near the beginning of the film.
At one point Erin proclaims: "Books can't fly and neither can babies". Both happened in the original Ghostbusters (1984) and Ghostbusters II (1989).
When Erin Gilbert is giving her presentation of Quantum Physics, she writes equations on a board, one of which spells out the equation [Pa/RA(NO+RM)alS+UD1ies/Lab]com, if you type this formula in a Google search you will be redirected to a Ghostbusters marketing website, an Easter egg present in the film. As of October 2017 the website has already been taken off line.
After Erin comes to Abby's lab and announces that she has been fired, Abby says, 'Unlike Columbia, this institute is 100% behind us.' This is a reference to Ghostbusters (1984), where Columbia University allowed its facilities to be used for filming as long as its name was never mentioned.
In some of the posters featuring Holtzman, on her proton pack is the number 2206. This is the same number as Dana Barrett's apartment in Ghostbusters (1984).
During the 1990s, Dan Aykroyd's concept for a third Ghostbusters film revolved around the Ghostbusters traveling to an alternate, hellish version of New York City. Columbia Pictures balked at the proposed $150m budget. Ultimately, Ghostbusters (2016) ended up with a $144m budget, although inflation means it cost less than Aykroyd's proposed sequel.
The role of Patty Tolan, played by Leslie Jones was originally written for Melissa McCarthy. Paul Feig realized that Melissa McCarthy had played similar characters in his previous films, explaining "I wanted to unleash Leslie on the public in the same way we unleashed Melissa on the public in Bridesmaids (2011), with a very showy role."
Jason Reitman, son of original Ghostbusters (1984) director Ivan Reitman, was asked in an interview if he would consider directing the reboot. Reitman joked that, based on his existing work, his version of the film would just be people talking about ghosts.
In the end credits, special thanks are given to "GB Superfan" Ryan E. Kemp who died in October 2015. Kemp had met with Paul Feig on two occasions and was positive about the prospect of this reboot.
At one point in the movie, Holtzmann says "they are heavier than you think" with regards to the proton packs. During the filming of the first two original Ghostbuster movies, the actors often complained about the weight of the proton packs.
When possessed Kevin shows the Ghostbusters the glory days of New York City and summons ghosts, there's an advertisement saying "That's a big" and showing a Twinkie, a reference to Spengler's 35 feet long and 600 pounds Twinkie metaphor in the original Ghostbusters (1984).
When the Ghostbusters' early version of the proton pack fails and gets crushed by the subway train, the sound it emits is the same sound of the Millennium Falcon hyperdrive failing in Star Wars: Episode V - The Empire Strikes Back (1980).
In the late 2000s, Harold Ramis and Dan Aykroyd supervised a script for a third Ghostbusters film written by Year One (2009) co-writers Gene Stupnitsky and Lee Eisenberg. Bill Murray later said, in an interview with GQ, that he never read the script after Year One was a commercial and critical failure. Later, Etan Cohen wrote a draft. Aykroyd vehemently denied a rumor that Murray shredded the script. During an appearance on the Howard Stern Show, Murray admitted he had not read that draft either.
Erin has a Apker Award from the American Physical Society on the wall in her office. This is a real annual award for outstanding achievements in physics by an undergraduate student.
The ghost Slimer got his name in the cartoon series The Real Ghostbusters (1986). His name is not spoken in any of the movies, but appears in the credits of Ghostbusters II (1989).
Emma Stone turned down an offer to star in the movie. She stated that while she liked the script, she did not want to commit to another potential series so soon after appearing in The Amazing Spider-Man (2012) and The Amazing Spider-Man 2 (2014).
During the climax, the number 1984 is seen on Jillian Holtzmann's Proton pack. 1984 the year the original Ghostbusters (1984) was released in theaters. It is also the year in which Kate McKinnon was born.
When the Ghostbusters are driving to the rock concert, they pass the New York Public Library, where the original opens with. They also pass the "docking" area where Ecto-1 pulled out of after their meeting with the mayor in the original Ghostbusters (1984).
Holtzman calls Pringles potato chips "salty parabolas". The shape of a Pringles potato chip really is a hyperbolic paraboloid or a saddle surface.
When the Ghostbusters open the container with the ghost for Dr. Martin Heiss, he jokingly calls the ghost "Casper" in reference to the children's cartoon character "Casper, the friendly ghost". The creators of Ghostbusters (1984) were sued by the owners of the "Casper" properties for $50 million plus the destruction of the film prints. because their logo looked too similar to their character "Fatso", a member of "The Ghostly Trio". But in 1986 the case was ruled in favor of "Ghostbusters". Nevertheless the live-action adaptation of Casper (1995) featured a cameo of Dan Aykroyd as Ghostbuster Ray Stantz.
Eliza Dushku was floated around as one of the members of the team with her name cropping up in some early credits works and the actress herself even dressing as a Ghostbuster for Halloween.
In an interview with 'Den of Geek', Paul Feig revealed that the first cut of the movie was 4 hours and 15 minutes long.
Even though the movie is set New York City, most of the filming was done on locations in and around Boston. These locations include Chinatown in Boston, Easton, the old South Weymouth Naval Air Station (now Union Point condo complex) in South Weymouth, Massachusetts, and the old Everett High School in Everett, Massachusetts. The set at Union Point was set out as a NY city street complete with street lights, lots of green screens and the focal point being a two story structure with a office building feel to it.
The four main cast members all joined the movie because they themselves were fans of the original Ghostbusters (1984) movie (and in Melissa McCarthy's case, The Real Ghostbusters (1986)).
There is also tribute to John Candy, who was originally approached to play Louis in the original Ghostbusters (1984) but turned down the part. The Dean of Higgins university, where Abby and Holtzmann work, is named Thomas Shanks. Tommy Shanks was one of John Candy's characters in SCTV (1976). John Candy is also featured in the original Ghostbusters music video.
Holtzmann's hairstyle and glasses resemble her counterpart Egon from Slimer! And the Real Ghostbusters (1988).
Rowan has a certificate for a Hughes Medal on his wall. This is an actual award that is given out biennially by the Royal Society of London "in recognition of an original discovery in the physical sciences, particularly electricity and magnetism or their applications".
As of July 2016 this film holds the title for 'most disliked' trailer ever on YouTube.
The studio had long wanted to make Ghostbusters 3 for many years. When Dan Aykroyd was asked many times about the third film, his answer was always yes on condition that if all the principle Ghostbusters (1984) cast members including Ivan Reitman who directed the first two films return. The only main problem according to the main players was Bill Murray himself who shows lack of interest in reprising the role of Peter Venkman. However, the cast did reprise their roles in the 2009 video game, which is unofficially considered the third film that takes place two years after the events of Ghostbusters II (1989). According to Reitman, when he met Murray in 2011, Murray already had shown loss of interest when the subject was brought up although there was no script at that time. The passing of Harold Ramis in early 2014 was the final straw that two weeks after that Reitman announced that he didn't want to direct it, resulting in Ghostbusters 3 being canned.
Higgins University is believed to be named after Steve Higgins who plays the dean. Higgins is a writer and producer on Saturday Night Live (1975). Director Paul Feig denies this.
Jennifer Lawrence and Rebel Wilson were considered by director Paul Feig for roles in the movie.
Anna Faris, Alyssa Milano, and Eliza Dushku were rumored or mentioned by Dan Aykroyd as potential female Ghostbusters, before the project was a reboot.
The character Jillian Holtzmann wears a necklace throughout the film in the shape of a U with a screw going through it. The Ghostbusters inspired Holtzmann's Screw U necklace pendant has since been created and is now being sold online.
The joke of Ed Begley Jr. being Ed Mulgrave Jr. as opposed to Ed Mulgrave Sr. is an homage to Ed Begley Sr. and Ed Begley Jr who are both actors.
A poster of the Boris Karloff film Isle of the Snake People (1971) is on display when the villain recreates the glory days of 1970s New York City. Such a recreation is complete with movie posters (Taxi Driver (1976)), neon signs, naughty businesses, billboards advertising products from the time period and even a sign celebrating the end of the Vietnam War.
Some scenes were filmed at the Ames family Stone Mansion at Borderland State Park in Massachusetts, where the Stone Lodge/Lake scenes for Shutter Island (2010) were filmed.
Leslie mentions that Rowan's clothes make him look like Captain Kirk. Chris Hemsworth played Captain Kirk's father in Star Trek (2009).
Four of the cast members, Kristen Wiig, Leslie Jones, Kate McKinnon, and Cecily Strong have been Saturday Night Live (1975) cast members. At the time of release, Melissa McCarthy had also hosted SNL four times. Of the original cast, Bill Murray and Dan Aykroyd were also SNL stars, while Harold Ramis was a writer for the Canadian sketch show SCTV (1976), co-starring Rick Moranis.
During the title sequence, there is a shot of the library of Columbia University. Parts of Ghostbusters (1984) were filmed at Columbia University.
This will be the 4th time Michael McDonald (Jonathan the Theater Manager) appears in a movie starring Melissa McCarthy. He also appeared in The Boss (2016), Spy (2015) and The Heat (2013).
Aldridge Mansion is loosely based on the Old Merchant's House on 4th street in Manhattan, which is also a museum open to the public.
Abby and Erin's hair inexplicably turning white towards the end comes from an episode of The Real Ghostbusters: "The Hole In The Wall Gang".
Erin notes that her red hair dye is called "Garfield." Though she says "the President [James A. Garfield], not the cat," the cat has a Ghostbusters connection of its own: Both Bill Murray and Lorenzo Music have shared the roles of Garfield the cat and Peter Venkman the Ghostbuster.
A third Ghostbusters film had been stalled in development for nearly 25 years, until director Paul Feig pitched a reboot instead.
Erin wears an MIT class ring on her right hand, visible in close-ups and in another scene she wears an MIT sweatshirt.
Mindy Kaling mentioned the idea of an all-female remake of Ghostbusters (1984) in her 2011 book "Is Everyone Hanging Out Without Me? (And Other Concerns)." She is not, however, involved with the making of this film.
In Trainwreck (2015), Amy Schumer's character is on a stalled subway train, standing next to Leslie Jones' character. She asks why is the train stalled and Jones says "Do I look like I work for the MTA?". In this film, Jones does work for the MTA.
In early pre-production, Anne Hathaway was reportedly considered for a role. The role was supposedly a doctor named Anna.
When Chris Hemsworth (an Australian actor) says "you know, an aquarium is like a submarine for fish", this could be a parody of an infamous comment made by Australian politician John Madigan at 02 February 2015 on ABC's "Q&A" program, in which he says "submarines are the spaceships of the ocean".
Martin Heiss' fashion sense is widely believed to be based on Paul Feig's own flamboyant fashion sense, but Feig denies this.
Jillian Holtzmann eats Pringles potato chips as she ghost hunts. In the original Ghostbusters (1984), Venkman has an open bag of Wise chips with him when he meets Walter Peck.
The car the Ghostbusters use which Patty got from her uncle is a 1983 Cadillac funeral coach 'Ecto-1'.
The extended cut runs 2 hours and 13 minutes, making this the longest Ghostbusters movie to date.
First Ghostbusters film to introduce another ghost of Slimer's kind, a love interest in the form of Slimerette.
Melissa McCarthy and Bill Murray previously co-starred together in St. Vincent (2014).
The character name Erin Gilbert is in fact a combination of two characters played by Julia Roberts. Erin is based on Erin Brockovich (2000), Roberts' award-winning role, while the last name Gilbert refers to author Elizabeth Gilbert, the author that Roberts played in Eat Pray Love (2010). Gilbert's book is also mentioned in the movie as well.
Katie Dippold wrote the screenplay. She also wrote the cop comedy The Heat (2013), which also starred Melissa McCarthy.
Five actors who appeared as the crew in Other Space (2015), created by Paul Feig, have roles--ranging from brief cameos to major parts--in the film: Neil Casey, Eugene Cordero, Bess Rous, Karan Soni, and Milana Vayntrub.
A cop says Kevin looks like DC Comics' Clark Kent, alter ego of Superman, Chris Hemsworth (Kevin) plays Marvel Comics' Thor.
Melissa McCarthy and Kristen Wiig were together on Bridesmaids (2011), also directed by Paul Feig.
Ghostbusters (1984) and Ghostbusters II (1989) followed a group of four men (three parapsychologists and one civilian) who run a ghost capturing business. This is a "genderswapped" reboot, following four women instead.
The Mercado hotel lobby is the same lobby set used for the Hotel Cortez in the TV show American Horror Story: Hotel.
Melissa McCarthy, Zach Woods, Jessica Chaffin, Michael McDonald, Adam Ray, Nate Corddry, and Steve Bannos all worked together on The Heat (2013).
The film reunites Justin Kirk and Elizabeth Perkins of Weeds (2005). Their scenes are in the extended version only.
Melissa McCarthy and Cecily Strong previously co-starred together in The Boss (2016).
The Aldridge Mansion may be named for Ghostbusters (1984) costume designer Theoni V. Aldredge.
Steve Higgins (Dean Shanks) and David Allen (Electrocuted Ghost/Sparky) previously starred together in the TV series Higgins Boys and Gruber (1990).
Kevin's last name is visible on his signed beefcake photos as Beckman, which resembles the last name of Bill Murray's character in the original movies, Peter Venkman.
The appearance of the Stay-Puft Marshmallow Man as a parade balloon is derived from "The Revenge of Murray the Mantis", an episode of The Real Ghostbusters.
Not counting this movie's mid- and post-credit scenes, Ernie Hudson delivers the final line in both this movie and the original "Ghostbusters".
Daniel Ramis: son of Harold Ramis has a small role as a Metal Head outside the concert Rowan attends.