Or you noticed and just forgot. Or you never noticed and didn't forget, since it's difficult to forget something you never noticed. Or you noticed and didn't give a shit. From TheMovieGuru and Premiere.com.
1. JOHN HUGHES IS MR. JOHNSON
At the end of the movie Anthony Michael Hall gets into a car being driven by the reclusive late director.
2-3. VANITY PLATES
The nerd's parents have the plate "EMC 2" referring to Einstein's theory. The truck dropping off and picking up the jock has "OHIOST" on its plate. This could either be the place he's being forced to attend pending a scholarship, his mean ol' dad's alma mater, or both.
4. TORCHED LOCKER
While it's easy to notice this, you probably didn't realize what it was at the time. During the opening montage, we see a locker that's been completely decimated by fire. Almost like a flare gun went of in it, right? (Yes, it did. That's Brian Johnson's locker.)
5. CARL WAS ONCE THE BIG MAN ON CAMPUS
The wise and sassy janitor was Man of the Year in 1969. Now, 15 years later, he's picking up after bratty little punks. Makes you wonder if one of the students in detention is also on the fast-track to a career in the custodial arts. (Bender is the obvious pick, but our guess is wrestler Andrew Clark. The scenario: His knee blows out during his freshman year of college, he loses his ride, and is forced to return home. With his glory days behind him and no discernible future--his dad disowned him for not being a winner--he's greeted with open arms by Shermer High School and offered the job after Carl is fired for drinking on the job and blackmailing teachers.)
6. HACKING WAS A PROBLEM IN 1984
Apparently so, or at least enough for the school to post a sign in the computer lab stating "Hackers Will Be Expelled." This is most likely a nod to early 80s films like Tron and Wargames, which opened up a world of possibilities for h@X0rzing. Shall we play a game? You bet your ass we shall.
7. GETTING STREAKY WITH IT
Bender (Judd Nelson) has a bluish-silver streak in his hair, which is quite noticeable on Blu-ray.
A few more trivia tidbits I lifted from IMDb:
Emilio Estevez was originally going to play Bender, but Hughes couldn't find someone to play Andrew Clark, so Emilio agreed to play Clark.
Molly Ringwald really wanted to play Allison but Ally Sheedy had already been promised the part.
Anthony Michael Hall's mother and younger sister play his character Brian's mother and sister in the movie.
Director John Hughes insisted that the entire cast and crew eat their meals on location in the high school cafeteria. Nicolas Cage was originally considered for the role of John Bender but the production couldn't afford his salary at the time. John Cusack was originally cast as John Bender, but John Hughes decided to replace him with Judd Nelson before shooting began.
Rick Moranis was originally cast as the janitor; he left due to creative differences and was replaced by John Kapelos.
The dandruff that Allison shakes onto her penciled drawing for snow was achieved by sprinkling Parmesan cheese.
John Hughes almost fired Judd Nelson because of his negative attitude towards Molly Ringwald off camera. Paul Gleason (Principal Vernon) convinced Hughes that Nelson was a great actor and was merely trying to stay in character.
It was originally suggested that there would be several sequels to The Breakfast Club, occurring every ten years, in which the group would get back together.
Any hope of a sequel to The Breakfast Club was dashed due to the volatile relationship between John Hughes and Judd Nelson. John Hughes has stated that he would never work with Nelson again.
At the time of shooting, Molly Ringwald and Anthony Michael Hall were the only Breakfast Club members of high school age, both being 16. Emilio Estevez and Ally Sheedy both were 22, and Judd Nelson was 25.
Jodie Foster was considered to play Claire and Brooke Shields was considered to play Allison.