Much like her character, Demi Moore (Jules) had a drug problem when she was cast in the film. One day, director Joel Schumacher actually demanded that she leave the set because she was really high. Moore had to go through rehab and promise to stay clean in order to play a character with a drug problem.
The "booga-booga" cheer that the friends do when they are celebrating or just in a good mood was not originally in the script. In a later interview, Rob Lowe (Billy Hicks) stated that the cheer came out of observing fans whispering about the stars of the movie and then laughing. The cheer itself makes fun of what these whispered conversations sounded like from a few feet away.
Singer John Parr, who co-wrote and sung the title song "St. Elmo's Fire" for the soundtrack, explained during a speech at the Children's choice awards in Sheffield that he was "not particularly thrilled" to be working on this film and that the song was written in honour of Paralympian and fundraiser Rick Hansen. He said that "the wheels" of the Man in Motion referenced in the lyrics was popularly thought to mean the wheels of Demi Moore (Jules)'s jeep, but actually refers instead to those of a wheelchair.
Emilio Estevez (Kirby Keger) and Demi Moore (Jules) began dating during the filming of the movie. He said he was "deeply in love with her." For a time they were even engaged, though they never married.
At the time of production, actor Rob Lowe (Billy Hicks) was the youngest of the lead cast (about nineteen) while actress Mare Winningham (Wendy Beamish) was the eldest having had already borne two children.
Director Joel Schumacher saw Demi Moore (Jules) walk down the hallway in his office's building and asked a colleague to run after her and find out if she was an actress. Schumacher's production office at the time was in the same place as that of John Hughes' office where Moore had just been visiting regarding a casting call.
Joel Schumacher originally had felt that Rob Lowe wasn't right for the part of Billy. Only after repeated phone calls from his agent and a passionate speech about why he wanted the part did Rob eventually get it.
The name of the higher education campus that is seen in the movie is "Georgetown University." All the major characters in the film's story attended this university together. After reading the script, Georgetown University administrators refused to allow producers to film on campus, so the on-campus scenes were filmed at the University of Maryland instead. No Georgetown University buildings appear in the film at all.
Each of the graduates holds fast to the unconditional acceptance and affection of their group, a safety net beneath them as they step into the adult world. "Our early life is a series of plateaus", explained writer-director Joel Schumacher, who added, "adulthood is a state that you are constantly defining for yourself as you go along, hoping that an 'adult' is what other people will see. In 'St. Elmo's Fire' we wanted to dramatize the passion and uncertainty of that time. We also wanted to make a point about self-created drama: When most of us look back on our twenties, we see that a lot of the incredible drama we went through was self-created. I hope that older people will be reminded of what they went through and younger people will see something of themselves and their own lives. Each of the friends faces decisions that will determine his or her future".
Director Joel Schumacher has said of the film's casting according to the book "You Couldn't Ignore Me If You Tried: The Brat Pack, John Hughes, and Their Impact on a Generation" (2011) by Susannah Gora, "a lot of people turned down the script . . . the head of [a] major studio called its seven-member cast 'the most loathsome humans he had ever read on the page'."
The movie's title theme song "St. Elmo's Fire (Man in Motion)" was originally written for disabled three time Paralympic Games gold medalist Canadian wheelchair athlete Rick Hansen who was raising awareness on a promotional "Man in Motion Tour" for spinal cord injuries at the time the film was being made.
The film's title, "St. Elmo's Fire", is derived from a real life meteorological phenomenon which is mentioned in the movie. It is also known as "St. Elmo's Light". According to website 'Wikipedia', it is "a weather phenomenon in which luminous plasma is created by a coronal discharge from a sharp or pointed object in a strong electric field in the atmosphere (such as those generated by thunderstorms or created by a volcanic eruption)".
According to director and co-scriptwriter Joel Schumacher's audio-commentary, co-screenwriter Carl Kurlander reportedly based Kirby Keger (Emilio Estevez)'s obsession with Dale Biberman (Andie MacDowell) on his own true-life university crush on a fellow student he had known on campus whilst studying at uni.
Jules (Demi Moore) is the only person of the seven central characters in the cast whose last name is never mentioned in the movie. Her full character name is Julianna Van Patten according to the movie's screenplay.
Mare Winningham (Wendy Beamish), whose character is Jewish, was raised a Roman Catholic and was non-religious at the time she shot this movie. About twenty years after making St. Elmo's Fire (1985), Winningham converted to Judaism.
The film's director Joel Schumacher said of this movie around the time the picture was made and released: "While going out in the world for the first time is a universal experience, there does seem to be a difference in young people today. In The Graduate (1967), the young person was confused and the older people were full of advice about how he should run his life, including getting into 'plastics'. Today, the young person is more likely to advise the older one".
The film's producer Lauren Shuler Donner, billed as Lauren Shuler on the credits, said of this movie: "'St. Elmo's Fire' confronts the problems of what happens to friendships after a life-change such as graduating from school, marriage, divorce or changing jobs. Unfortunately, old friendships tend to dissolve as one moves on in life. The friendships of our seven characters are an important element in each of their lives, but now they're setting out in different directions and will form new bonds".
Of the considered "core" members of the so called 1980s "brat pack", this movie had the most of them cast in the one film, more than any of the other pictures of the period. These core "Brat Pack" members included Emilio Estevez (Kirby Keger), Rob Lowe (Billy Hicks), Andrew McCarthy (Kevin Dolenz), Demi Moore (Jules), Judd Nelson (Alec Newbary) and Ally Sheedy (Leslie Hunter). Core "Brat Pack" members not in St. Elmo's Fire (1985) were Molly Ringwald and Anthony Michael Hall but the pair had appeared in the same 1985 year's The Breakfast Club (1985) alongside St. Elmo's Fire (1985)'s Nelson, Sheedy and Estevez, taking that film's "Brat Pack" total to five, but this being one less "Brat Pack" member than St. Elmo's Fire (1985), which had six. Both of these "Brat Pack" movies though were first released in the same 1985 year.
Andrew McCarthy (Kevin Dolenz)'s character has several witty lines that are lifted directly from Ian Shoales, a fictional pop-culture critic created by Merle Kessler of the Duck's Breath Mystery Theater. Ian Shoales appeared on NPR's "All Things Considered," as well as MTV's The Cutting Edge Happy Hour (1983). The "St. Elmo's Fire" credits give "special thanks" the Duck's Breath Mystery Theater.
David Foster and handicapped athlete Rick Hansen were longtime friends, who both needed a musical inspiration at the same time - Foster needed a theme song for his movie, Hansen a theme to spark interest in his " Man in Motion" world tour. Hansen was circling the planet in his wheelchair to raise funds and awareness for his spinal injury research foundation. The song "St. Elmo's Fire (Man in Motion)" was born, with a portion of the proceeds going to the foundation.
The production notes for this film state: "An outstanding ensemble of some of today's most talented and accomplished young actors stars as a tightly knit group of recent college graduates who face their 'freshman year of life' . . . Following their graduation, the intimate group of seven young men and women must confront, as individuals, all the issues of life after college in the 1980s. In their commitments, careers and relationships, the choices each makes will shape a lifetime, and cause conflicts that test even their treasured friendship".
Film critic Gene Siskel compared this movie unfavorably with "About Last Night". He said :"This is the movie "St. Elmo's Fire" wanted to be and missed by a mile. This is a movie that documents a rite of passage in so many people's lives --from individual to couple."
The trivia item below may give away important plot points.
Ally Sheedy (Leslie Hunter) was horrified by her sex scene with Andrew McCarthy (Kevin Dolenz). It wasn't until the day of filming that she realized it wouldn't be a simple fade out before any of the naked stuff happened (she wore a body suit). But both McCarthy and Joel Schumacher made the process more comfortable. "He knew I felt awkward, and he shot it fast," Sheedy said of her director. "He didn't draw it out into this painful exercise at all." And a mishap actually added some laughter to the scene; when the shower door was pushed out of frame, it was an accident that stayed in the film, much like Sheedy's reaction: "It was my real laugh there," she says.