Development Hell: In 2009, Warner Bros., The Kennedy/Marshall Company and Leonardo DiCaprio's Appian Way Productions were in the early stages of creating another adaptation of the novel. They intended to "examine the more nuanced details of the book" rather than remake the original film by Petersen. In 2011, producer Kathleen Kennedy said that problems securing the rights to the story may mean a second adaptation is "not meant to be".
Follow the Leader: To Peer Gynt. Bastian expies Peer Gynt on several occasions: Bastian is known for his tall tales, is called a liar, and has, like Peer, a gift of fantasy. When slipping away to Fantasia, he piles up several wishes to hide his true self, gradually losing it, and is at the end of the story, about to lose himself completely, ending up in a city of madmen. Oh, and before that, he was about to proclaim himself emperor. Like in the Cairo madhouse, the people of the city of madmen see nothing but themselves. At the end, with his memory of his human life totally gone, Atreju intervenes on behalf of him, doing the part of Solveig (replacing love with The Power of Friendship), giving Bastian the insight he needs to return home. Another similarity is the focus on a simple phrase that can be interpreted in multiple ways: "Be yourself" and "Do what you wish" for Peer Gynt and The Neverending Story respectively.
Box Office Bomb: The second and third movies in the U.S. For The Next Chapter, Budget, $36 million. Box office, $17 million (domestic), $56,468,971 (worldwide). This led to the third unrelated film having a budget of $17 million. Box office, $5 million in Germany, but allegedly not even 5 figures in the States, where it screened in limited release, was ripped to shreds, and eventually came Direct to Video without Warner's involvement (Disney/Miramax distributed it instead).
Dawson Casting: The "high school students" in III are in their mid-20s - or older. Similarly, Julie Cox is cast as the "Childlike" Empress despite being 21 by the time the film came out, which is noticeable in that she was actually taller than Jason James Richter, who played Bastian in that film.
Disowned Adaptation: Michael Ende filed an injunction to stop the production of the film, or failing that prevent them from using the title of his novel. He was unsuccessful, and demanded that his name be removed from the credits. He particularly took issue with the film's ending, which shows Fantasia restored with little creative input from Bastian and also shows Falkor crossing into the real world (noted to be impossible in the novel, as Fantasticans who enter the real world become lies). This is why Ende's name is not referenced in the film's opening credits. Given that the first film was a much closer adaptation (of the first half of the book, at least), one can only imagine what he'd think of the other two.
Enforced Method Acting: That look of shock on Atreyu's face and how dazed he looks getting up after he kills Gmork? That was real. Apparently, they didn't realize how heavy the mechanical wolf puppet could be, and when they shot the scene, it almost knocked out Atreyu's actor. They decided not to try for a second shot after he revealed the claws almost poked out one of his eyes too.
Executive Meddling: After the first film's test screenings revealed that audiences were not enthused with Klaus Doldinger's score, the studio commissioned Giorgio Moroder to replace some of the original music with his own. Wolfgang Petersen was not pleased, though the title song became one of the most memorable aspects of the film to many viewers.
Franchise Killer: The third film. Characters didn't retain their original personalities, Atreyu being absent and the series' iconic theme song at the end of the movie (which reused a "Born to Be Wild" rendition) were the final nails in this film's bookcover.
One-Take Wonder: Noah Hathaway almost lost an eye during the fight-scene versus Gmork. One of the claws on his giant paws poked him in the face. The robot was also so heavy that he lost his breath as well when he was hit to the ground by it. They only made one shot due to the risk that he would get seriously wounded.
The Other Darrin: The second movie has only one of the main actors from the first movie (Thomas Hill as Mr. Coreander), and the third movie doesn't have any of them. Most noticeably, Bastian's father has inexplicably gotten younger between the first and second films.
Pop Culture Urban Legends: Contrary to Internet rumor, the horse did not really die during the filming of the Swamp of Sadness scene. As confirmed by German magazine interview with Noah Hathaway shortly after the movie, and in the years since at conventions, the horse was given to Noah at the end of filming but due to the cost of transportation, need for quarantine, and sterilization, the horse was left behind in Germany.
Troubled Production: As the most expensive movie made in Germany up to that time (and, indeed, the most expensive movie made outside the US or USSR at that time), it's hardly surprising that things went wrong in many ways, as actors got injured, the weather was scorching hot and scenes were cut after the Swamp Sadness spent too much money. Producer Dieter Geissler decided not to endure everything again by spending a whole year with pre-production when doing The Next Chapter.
Ygramul the Many was intended to appear—the sequence was scripted and storyboarded—but cancelled due to the special effects limitations of the time. This scene would have explained why the gnomes are seen giving Atreyu and Falcor heavy doses of medicine, as Ygramul was a hive-minded swarm of deadly poisonous wasps.
The same goes for the Wind Giants from the book—when the crew weren't able to convincingly create giant cloud beings, the scene was re-cut into Atreyu and Falcor's close encounter with The Nothing (the line "Look Atreyu, The Nothing!" from Falcor being dubbed in).
Vaporware: German game developer Discreet Monsters' The Real Neverending Story, which wasn't really getting anywhere even before Discreet Monsters was felled by the end of a tech bubble. The main personnel involved eventually produced a much less ambitious game, Auryn Quest.