- Awesome, Dear Boy/Promoted Fanboy: John Neville was not a film actor at the time, preferring the theater. However, he was also a big Monty Python fan so he readily agreed to take the lead.
- Box Office Bomb: Budget, $46.63 million. Box office, $8,083,123. This film's implosion, along with the severe financial failure of Ishtar and to a lesser extent other movies such as Leonard Part 6, led to Columbia merging with Tristar and Coca-Cola selling their whole film business to Sony. It didn't help that the film was released that only 117 prints were made for the American market, which is unusual for a film of this budget. The film also did not get production company Allied Filmmakers off to the start they would have hoped for, with most of the label's films being a critical flop, a commercial flop, or a flop of both kinds. That said, this is one of the films that is an Acclaimed Flop, having a 92% on Rotten Tomatoes.
- Creator Backlash: Special effects supervisor Richard Conway felt immense guilt over his complacency in endangering young Sarah Polley, even breaking down in tears when the two rewatched the film together years later and reached one such scene where the danger was quite apparent.
- Deleted Role: Christopher Lambert filmed scenes that were cut from the final print.
- Doing It for the Art: Robin Williams was a last-minute casting after the budget had run out, and performed his role uncredited and unpaid.
- Dyeing for Your Art: The main male cast all shaved their heads bald to accommodate the wigs they would wear.
- Harpo Does Something Funny: Oliver Reed claimed that Terry Gilliam pretty much let him do what he wanted.
- Invisible Advertising: Where the U.S. release was concerned.
- On-Set Injury: During the scene in the boat, the horse playing Bucephalus got spooked and the stuntman Angelo Ragusa rode it into the water to keep it from trampling Eric Idle and Sarah Polley. Unfortunately, it dislodged a plastic explosive, which went off close to Polley and led to a hospital visit. In between this and other dangerous stunts (being held in harness with no safety net, explosives going off too close to her, working while deeply ill) Polley was traumatized for years by the experience, and Eric Idle once said "It was amazing we never lost anyone.".
- Screwed by the Studio: It was greenlit by Columbia Pictures, then under the management of eccentric British producer David Puttnam, who wanted to make Columbia the anti-Hollywood of the Hollywood studios and flopped miserably (another major failure under his regime, Ishtar, was beset by issues — issues exacerbated by Puttnam leaking info about the film's troubles to the press in retaliation against Warren Beatty). Columbia cleaned house and hired new management who didn't care about the remaining Putnam films, so Munchausen was dumped into 117 North American theaters with next to no publicity. It made only $8 million in the end. It still managed a few Academy Award nominations for its technical strengths (though it didn't win any) and did well with critics; today it's considered one of Gilliam's best films.
- Throw It In: It shouldn't be a surprise that Robin Williams' dialogue was ad-libbed.
- Troubled Production: Big time. The film went overbudget, the plane that had the costumes and prop were stuck in an airport in another country due to a custom strike, a lot of the animals for the film died and had to be replaced, etc. Producer Thomas Schuhly acted like a prima donna, refusing to sign forms and refusing to get along with the English crew and the complex relationship between the UK crew and the Italian crew. And because Columbia Pictures was undergoing a regime change at the time and the new bigwigs didn't want to support a film this troubled, they didn't put much money into the marketing campaign or even give it a wide North American release, and it flopped. Eric Idle called it "A truly horrible experience and even remembering it is a bit of a nightmare."
- Sarah Polley, who was nine years old at the time of filming, described it as a traumatic experience."[I]t definitely left me with a few scars ... It was just so dangerous. There were so many explosions going off so close to me, which is traumatic for a kid whether it's dangerous or not. Being in freezing cold water for long periods of time and working endless hours. It was physically grueling and unsafe."
- As a harbinger of the film's series of unlucky incidents, the start of filming had to be postponed for a week due to Dante Ferretti's elaborate set not being ready in time. A crane collapsing into it didn't help matters, postponing the film's start by another week.
- Sarah Polley, who was nine years old at the time of filming, described it as a traumatic experience.
- Wag the Director: When Eric Idle first put on the costume for his character, he complained that the costumes huge thighs made him look like he "had no dick" and half-jokingly demanded that the costume department make him a false one. They complied and it remains in Idle's possession to this day.
- What Could Have Been:
- Sean Connery was considered for the King of the Moon. Then the role was scaled down and Connery didn't think it was "kingly" enough. He was also considered for the Baron.
- Gene Wilder and Walter Matthau were considered for The King of the Moon.
- Terry Gilliam originally wanted Peter O'Toole to star as Baron Munchausen. Jon Pertwee was also considered.
- Gilliam also wanted Marlon Brando to play Vulcan, even meeting him at his home. They reportedly had an enjoyable afternoon until Brando's agent showed up.
- Michael Palin was originally cast as the Prime Minister of the Moon but the character was written out of the film. As a consolation Gilliam offered him a cameo role as a man who dies while singing a song, but Palin declined. Gilliam took the cameo role himself.
- Originally, Gilliam planned to have a whole herd of cows in the Vulcan set. But because of escalating costs and a revised budget, he was only allowed one.
- Vindicated by Cable: Yet another movie saved by HBO.
Trivia / The Adventures of Baron Munchausen