Defictionalization: The Taco Bell logo seen in this movie was later used as a tie-in by the restaurant and eventually became the basis for their current logo. It turns out the heads of Taco Bell at the time were big fans of the movie and did so as a shout-out.
Doing It for the Art: Nigel Hawthorne, inexperienced in cinema, took the role of Cocteau to prove that he had screen presence for the producers of The Madness of King George. Hawthorne wanted to reprise the stage role for the movie version. As it transpired this was unnecessary as Hawthorne was the producers' automatic choice for the lead.
Dueling-Stars Movie: Stallone vs. Snipes. Most of the posters had this phrase and nothing more.
Early Draft Tie-In: The comic book keeps the sub plot about Spartan's daughter living with the sewer people.
Looping Lines: The "Pizza Hut" edit of the film required a bit of ADR juggling, nonetheless the fact that multiple main characters are clearly saying "Taco Bell" in close-up shots gives away the dubbing.
No Stunt Double: According to Denis Leary, Wesley Snipes insisted on doing his own action scenes. It got to the point where the crew would wait for Snipes to leave for the day and then film scenes with his stunt double.
One for the Money; One for the Art: Nigel Hawthorne appeared in this film because he had little feature film experience and felt he needed to prove he had screen presence because he wanted to play King George III in the then-upcoming film adaptation of The Madness of George III (a role he'd played on stage). As it turned out, he hadn't needed to go through the miserable experience of making Demolition Man because he'd always been the only choice to play George III.
The Other Marty: Lori Petty was originally cast as Huxley, but was fired after two days of filming due to what Joel Silver described as "creative differences". Petty attributed it to personality differences, as she and Sylvester Stallone did not get along, and said "Sly and I were like oil and water."
Saved from Development Hell: The original draft of the movie was sold in 1988. It had a serious, darker tone and had Spartan ending up with his much older wife. The writer wanted Mickey Rourke to star.
Science Marches On: Among the things listed as "not good for you, hence illegal" are spicy foods. Since the movie came out, though, spicy foods have been shown to help burn calories and reduce blood pressure. Also, dark chocolate has been shown to have antioxidants which can reduce free radicals in the body, lowering risk of cancer.
Spared by the Cut: Amongst the deleted material, Zachary Lamb was originally shot by Phoenix as the latter stole a car and would die in Spartan's arms.
Stillborn Franchise: In 1993, US Magazine reported a sequel was planned for 1995. In 2006, Sylvester Stallone was asked about a sequel and he said, "I'd like to make a sequel to Demolition Man, but I believe that ship has sailed and maybe there are more challenges waiting on the horizon." On May 4, 2020, Stallone said a sequel is in development.
Uncredited Role: Fred Dekker did uncredited re-writes on the script. When he was brought on, the script began in the future and Spartan was introduced when he was brought out of suspended animation. Dekker suggested that this movie open with a prologue set in 1996 to showcase Spartan and Phoenix in their natural environment, saying that "If you don't show Kansas, Oz isn't all that special."
Unintentional Period Piece: The whole film's premise of a future society where everything bad you say and do is banned is a pretty clear product of the Early '90s backlash to the concept of "Political Correctness". (Although looked upon through the lens of late 2010s eyes, the "backlash" part falls into YMMV as a number of statements made in the film.)
Vindicated by Cable: Wasn't particularly popular in its day, but now it's a Cult Classic that's beloved by fans of 90s action movies. It helps also that, much like Last Action Hero, more viewers today understand that it's not really an unironically straight action film, and better recognize the satirical aspect that caught contemporary critics and audiences off-guard.
In some early drafts, Lenina Huxley would have been revealed to be John Spartan's daughter. Obviously Lenina being John's daughter would have eliminated the romance angle for the two characters.
Another draft of the script was for Spartan to have a daughter (named Katie Spartan) be a resident of the Wasteland and one of Edgar Friendly's Scraps. During the shootout in the Wasteland, the woman Spartan was protecting was Katie, and she would later appear at the end, alongside Friendly.
When Sylvester Stallone got on board, he tried to convince Jackie Chan to take the part of Phoenix, which would have made Huxley's Saw It in a Movie Once moment a whole lot funnier. He turned down the role, as he didn't want to confuse audiences by suddenly appearing as a villain.
It was originally planned to have Spartan and Phoenix meet face-to-face without a fight, but then it was decided that it would be much better if they tried to kill each other.
For the pinball table:
Wag the Director: According to artist Doug Watson, his backglass artwork proposals were repeatedly rejected by Wesley Snipes, who wanted to ensure his career wasn't jeopardized by having him look like a crazed character. Linda Deal did the final backglass art.