18 details you probably missed in 'The Breakfast Club'

"The Breakfast Club" opens with a David Bowie quote from his song "Changes."

The lyrics resonate well with the movie's message, and according to the Daily Beast, the quote was suggested by Ally Sheedy, the actress who played Allison.

The song has appeared in other beloved movies, too, such as "Shrek 2" and "Confessions of a Teenage Drama Queen."

The name of the school in "The Breakfast Club" — Shermer High School — is clearly shown at the beginning of the movie.

The fictional suburban high school was also the setting for a number of the late John Hughes' famous movies.

Like "Ferris Bueller's Day Off," the shots of the building were actually filmed at Glenbrook North and Maine North high schools in the suburbs of Chicago.

Though the majority of the movie takes place on the library set, the opening scenes show other parts of the high school.

Shots of the cafeteria — complete with signs about lunch tickets and piles of snacks — make the school setting more vivid.

Viewers also catch a glimpse of the school bulletin board, which features a book cover with the school's name on it.

During the movie's introduction, a guidance counselor's office is shown when the "basket case" student is mentioned in the voice-over.

The desk in the office is full of recognizable therapy tools, such as the Rorschach inkblot tests.

There's also a book titled "I'm OK – You're OK" on the desk, which is a real 1960s self-help book.

In another opening shot, the camera pans past a plaque for the school's "Man of the Year" award.

Right in the middle of the plaque, for the year 1969, is Carl Reed — also known as Carl the janitor, who shows up later in the film.

Brian's mother — who was actually played by Anthony Michael Hall's real-life mom, Mercedes — drops him off for his detention at the beginning of the movie.

After being scolded for landing himself there, Brian gets out of the car, and its license plate is visible for a moment.

The plate number is "EMC 2," which is probably a reference to Albert Einstein's famous physics equation: energy equals mass times the speed-of-light squared.

We later find out that Brian is a member of the physics club and a brainiac, so the license plate serves as a fitting introduction.

At one point, Brian stands next to a sign showing the library rules, many of which the main characters end up breaking.

But what's more interesting about the sign is that someone penciled in a juvenile joke.

The top of the sheet reads, "In order to maintain a pleasant atmosphere in which to study we ask students to please," after which someone added, "blow each other."

Allison steals from the school and other students throughout the film, and it goes largely unnoticed by the other characters.

Before she even speaks her first line, she steals John's knife, and she later steals the lock from his locker.

She eventually comes clean about one of her thefts when she admits to stealing Brian's wallet.

When Carl the janitor walks into the library, a poster advertising a college and career fair presented by Oakton Community College is visible on the door next to him.

The poster says the fair's date is Tuesday, February 19, 1980.

"The Breakfast Club" premiered on February 15, 1985, and was filmed in 1984, so by the time the students were in detention, the fair had long since passed.

February 19, 1980, was a Tuesday and Oakton Community College is a real school in Des Plaines, Illinois — where part of the movie was filmed — so in all likelihood, this is probably a real poster for an old event.

John wears several different decorative pins on his shirt and jacket, but the majority of them aren't shown clearly enough to read.

The only legible pin is on his glove and reads "Not Saved," which fits his criminal, bad-boy persona.

When Vice Principal Vernon catches John playing basketball in the gym, the student has swapped one of his signature black boots for a white sneaker.

On his way out the door, he leaves the sneaker in the middle of the court and grabs his other boot and jacket from the sidelines, leaving where he got the shoe a mystery.

The scene where the characters each reveal why they're in detention is an emotional moment that lets them bond with each other. It also features many of the film's most iconic lines, like "When you grow up, your heart dies."

Like other parts of the movie, much of this scene was reportedly ad-libbed by the actors.

Director of photography Tom Del Ruth told the Huffington Post in 2016, "John was very accepting of suggestions from the actors. He wanted them to feel free and that gave them a lot of latitude."

He continued, "If there was a line or two or even a paragraph that lent itself to the character or enhanced the story, John was would simply rewrite on the spot."

While talking to Claire as they smoke, John uses a makeup brush from her compact to brush his teeth.

Later on, when she gives Allison a makeover, Claire, unfortunately, uses that same brush to apply makeup on Allison's face.

The students are in the library for a nine-hour detention session, so they predictably struggle to find ways to kill the time.

Despite how clearly bored the students are, they never attempt to use the computers in the room, or even acknowledge them.

Though the options for fun on a 1980s library computer were admittedly limited, it's odd that not even "the brain" Brian tried to use one.

While the group is trying to get Claire to admit whether or not she's a virgin, Allison lies about her own sexual experiences.

At one point in the conversation, when she's saying she's had sex with her therapist, Brian seems to start laughing.

He ducks his head for a second before pulling himself into a different sitting position with a more concerned expression on his face. But it seems that the actor was trying not to smile as he listened to the dialogue.

After they kiss, Allison grabs the patch off of Andrew's jacket.

It's a cute moment, as she smiles and waves with the patch before getting in her car. But it also shows how she's grown as a character — she isn't as secretive about her acts of thievery.

At the beginning of the film, when Andrew's dad drops him off, he asked his son, "You wanna blow your ride?" in reference to his college wrestling scholarship.

When he comes to pick his son up from detention at the end of the film, the license plate of the car is visible and reads, "OHIOST," so it wouldn't be a stretch to assume that Andrew plans to wrestle at Ohio State University.

The legendary writer and director wasn't known for appearing on screen. In fact, he didn't even make many public appearances.

But he can be seen briefly at the end of "The Breakfast Club" as Brian's dad.

According to his IMDb page, the only other films he made cameos in were "Ferris Bueller's Day Off" and "Class Reunion."