| Spoiler warning: The following contains plot details about|
the entire movie.
Upon falling asleep that night, Nemo is approached by figures from the parade. The circus organist introduces himself as Professor Genius and claims that they had been sent on a mission by King Morpheus, the king of a realm named Slumberland. The mission involves Nemo becoming the playmate of the princess, Camille. Although Nemo initially has reservations about interacting with royalty of the opposite gender, he decides to set off to fulfill his mission after being persuaded with a gift box of cookies from the princess.
Nemo is taken to Slumberland in a dirigible which he is allowed to drive, causing some chaos and is introduced to King Morpheus, who doubles as the circus ringmaster in Earth. Morpheus reveals that he summoned Nemo to become his heir to the throne. Morpheus gives him a golden key that opens every door in the kingdom and warns him of a door with a dragon insignia that must never be opened.
Nemo is introduced to Princess Camille and the pair roam the entirety of Slumberland together. Afterward, he meets the mischievous clown, Flip, who upsets a group of cops which forces him and Nemo to hide out in an underground cave. There, Nemo discovers the door that Morpheus had warned him not to open, but Flip tempts Nemo into unlocking the door which unleashes the dreaded Nightmare King.
Nemo rushes back to Morpheus' castle in time for his coronation ceremony where he is handed the royal scepter, the only thing capable of defeating the Nightmare King should he ever return to Slumberland. In the middle of a dance session between Morpheus & Genius, the Nightmare King reaches the castle and steals Morpheus away. As the partygoers search for a scapegoat, Flip reveals that Nemo was responsible for the Nightmare King's escape since Morpheus gave him the key. Nemo wakes up in his home which floods with seawater and ejects him into the ocean. Genius discovers Nemo and tells him not to blame himself for what has happened.
When they return to Slumberland, Flip reveals that he has a map to Nightmare Land where Morpheus is currently being held. Nemo, Camille, Flip and Genius set off in a tugboat in search of Morpheus. They are soon sucked into a whirlpool and they find themselves in the monster-infested Nightmare Land.
The four of them come across a group of shapeshifting goblins who wish to aid in the quest to find Morpheus. The Nightmare King sends a flock of frightening giant bats to seize the rescue party. Nemo tries to use the scepter, but he wakes up in his bed instead where goblins appear in his room.
The group travels to Nightmare Castle by flying through a hole in the sky. However, they get imprisoned in the castle where the Nightmare King demands possession of the scepter. Nemo uses the scepter to finally eliminate the Nightmare King once and for all & Slumberland celebrates the fall of the Nightmare Kingdom.
Camille escorts Nemo home on dirigible & they share a kiss after which Nemo wakes up in his room where he apologizes to his mother for breaking his promise and trying to take the pie. Nemo's parents also agree to take him to the circus.
Nemo is shown looking out the window as he reflects on his adventure.
- Gabriel Damon as Nemo: the protagonist. He is a human boy living in New York City who is taken to Slumberland to be the official playmate of Princess Camille; in actuality, however, he is being summoned to be the heir to the elderly King Morpheus. He is given the key to Slumberland, but is warned by the king to leave a door with a coiled dragon emblazoned on it closed. Sadly, he opens the aforementioned door when he is tempted by Flip and goes on a quest to restore Slumberland to its rightful glory, save King Morpheus and defeat the Nightmare King.
- Mickey Rooney as Flip: a supporting protagonist. Described as a "frightful fellow" by Professor Genius, he is wanted throughout Slumberland for "having fun" (the bounty on his head is a sizeable one) and his only friend is his partner-in-crime: a bird named Flap. He tricks Nemo into accidentally releasing the Nightmare King and blames him for the ruin of Slumberland. He is in possession of a map of Nightmare Land (hand-drawn and written in his own special code) and serves as the guide to the Nightmare Castle until he is replaced by the Boomps. He has a serious smoking addiction. In the real world, he is a clown in a circus that stops in Nemo's town.
- René Auberjonois as Professor Genius: King Morpheus' advisor and a supporting protagonist. He comes to the real world to bring Nemo to Slumberland. A sophisticated man, he is quite punctual and prefers order as opposed to madness. He is quite a dancer, as he dances quite a bit during Nemo's coronation ceremony. In the real world, he is an organ player in a circus that stops in Nemo's town.
- Danny Mann as Icarus: a flying squirrel, Nemo's best friend and a supporting protagonist. Icarus is Nemo's only friend from the real world. He shows great concern for Nemo's wellbeing in a sense similar to that of two siblings. He speaks a mix of both squirrel and some English. His screech is painful to the ears of the Boomps. He detests being called a "little rat" (which Princess Camille mistakes him for). Unlike other squirrels, Icarus eats human food, like cookies. His initial relationship with Princess Camille, though rough, eventually changes for the better.
- Bernard Erhard as King Morpheus: the elderly ruler of Slumberland and a supporting protagonist. He has protected Slumberland for years with the help of the royal scepter: an ancient weapon of great power. Though he is a child at heart, he knows when to be serious. He has Nemo brought to Slumberland so that he may become his heir to the throne. He gives Nemo the key to Slumberland, which can open any door; however, he warns Nemo of one door with a dragon symbol emblazoned on it that must never be opened. Like Professor Genius, he is quite a dancer, as he dances alongside the Professor during Nemo's coronation ceremony. When Nemo accidentally releases the Nightmare King, King Morpheus is captured and Nemo has to go and rescue him from Nightmare Land. In the real world, he is the ringmaster of a circus that stops in Nemo's town.
- Bill Martin as the Nightmare King: the main antagonist. He is a demonic creature who was locked behind a massive door until he was accidentally set free by Nemo, who was given the key to the door by King Morpheus. Once free, he captures King Morpheus as revenge for his imprisonment and then retreats to the Nightmare Castle. When Nemo goes to the castle to save King Morpheus, the Nightmare King has his minions capture Nemo's friends (Professor Genius, Flip and Princess Camille). He is shown to be quite temperamental, as he destroys several minions for the failure of just one of his underlings (the general of his army). The only thing that can defeat him is the legendary royal scepter.
- Laura Mooney (Hiroko Kasahara in the Japanese adaptation) as Princess Camille: the daughter of King Morpheus and a supporting protagonist. Though she initially acts somewhat spoiled, she eventually grows to like Nemo. She also grows fond of Icarus (and vice versa, despite a rough start). When her father is kidnapped by the Nightmare King, she takes over as ruler but decides to join Nemo in his quest to save King Morpheus. In the real world, she is the daughter of the ringmaster of a circus that stops in Nemo's town.
- Greg Burson as Nemo's father and Flap
- Jennifer Darling as Nemo's mother
- Neil Ross as Oompa
- Alan Oppenheimer as Oomp
- John Stephenson as Oompo and the Dirigible Captain
- Sidney Miller as Oompe
- Michael Bell as Oompy
- Kathleen Freeman as the dance teacher
- Bever-Leigh Banfield as the woman
- John Stephenson as the dirigible captain
- Bert Kramer as a goblin: A hideous creature that serves as a member of the Nightmare King's army. They are sent by the Nightmare King to ensure that Nemo doesn't reach his castle and free King Morpheus. Though the goblins succeed in capturing most of Nemo's friends, they fail to capture Nemo himself and, when the Nightmare King finds out, he kills them all in a fit of rage. The only goblins to survive are the Boomps (who, in contrast to the other goblins, are not hideous and are actually friendly).
- Beau Weaver as a policeman
- Sherry Lynn as Bon Bon
- Guy Christopher as a Courtier and a Cop
- Nancy Cartwright and Ellen Gerstell as pages
- Tress MacNeille as an elevator creature
- Michael McConnohie as an etiquette master
- Michael Gough as a teacher
- Michael Sheehan as a fencing master
- June Foray as the librarian
- Gregg Berger as the equestrian master
In 1977, producer Yutaka Fujioka flew to Monterey, California to convince the descendents of Winsor McCay to allow him to obtain the film rights to the “Nemo” comic strip. He originally approached George Lucas in a year later to help produce the film, but Lucas found problems with the storyline & declined. Fujioka also approached Chuck Jones, but he also declined.
The film was officially announced as a project in 1982 and in February of that same year, the company TMS/Kinetographics was formed in America to produce Nemo, and the best staff from around the world were gathered together to begin production. Gary Kurtz was appointed producer of the American production side and hired Ray Bradbury and later Edward Summer to write screenplays. Kurtz would eventually step down in the fall of 1984.
In the early 1980s, both Hayao Miyazaki and Isao Takahata were involved with the movie, but later parted ways due to creative differences; essentially, Miyazaki did not seem to be keen on the concept of an animated feature created by him where everything was a dream, and Takahata was more interested in creating a story depicting Nemo's growth as a boy. Miyazaki later described his involvement on the film as "'the worst experience he has ever been through'".
The directors who succeeded the duo were Andy Gaskill and Yoshifumi Kondo, whom both exited production in March 1985 after completing a 70mm pilot film. Osamu Dezaki was also brought into direct at a brief point and too completed a pilot film, but left as well. A third pilot film was made by Sadao Tsukioka but has yet to become publicly available.
Brad Bird and Jerry Rees also worked on the film through the American department as animators for a month, while at the time were also working on an unproduced adaptation of Will Eisner's “The Spirit with Gary Kurtz” and during production, they would regularly ask animators what they were doing, the response they were commonly given was "we're just illustrating what Bradbury is writing.”
Upon meeting Bradbury in person and asking him about the story he was writing for the film, he replied, "I'm just putting in writing what these wonderful artists are drawing". Bird and Rees soon left the project after their meeting with Bradbury. When all of these people had left, Fujioka had drafts done by Chris Columbus, Mœbius, John Canemaker, and many others.
Then, he then re-hired Summer to do yet another screenplay. Subsequently, Richard Outten was hired to work from Columbus' screenplay while Columbus was busy with his directorial debut, Adventures in Babysitting. Many Disney Studio animators including Ken Anderson and Leo Salkin worked on individual sequences, and John Canemaker, Corny Cole, and Brian Froud provided visual development. Frank Thomas, Oliver Johnston and Paul Julian consulted to the production.
The world-famous Sherman Brothers (also known as Richard M. Sherman and Robert B. Sherman) were hired to write the songs for Nemo. This was their first anime film, though not their first animated film; the pair had previously worked on several projects for Disney, including The Jungle Book and Hanna-Barbera's Charlotte’s Web.
Little production progress on the film was made until January 1988 when the many ideas pasted on the walls of the Los Angeles studio were whittled down in order to create the storyboard from which the film would be made. It was at this point, Thomas and Johnston recommended William T. Hurtz as the director of the American production side and TMS hired Masami Hata, a former Sanrio film director, as the appointed director at the TMS studio in Japan.
The actual animation for the completed film was commenced in June 1988, as TMS was just completing “Akira” and the success of that film in Japan further helped TMS finally start production on Little Nemo. Even though it derived from an American comic strip, Little Nemo was animated by the Japanese company Tokyo Movie Shinsha and thus is often considered an anime film, even though it was a joint production of Japanese and American animators and production companies.
The English dub of the movie was released three years later in the United States in 1992 in 579 theaters on August 21, 1992 through Hemdale Film Corporation. and the Re-Release in the United States in 1995 in theaters on May 26, 1995 through Universal Pictures and Amblinmation
Eleven minutes were cut from the film in order to secure a G rating.
In March of 2005, “Little Nemo” was given a very limited re-release in the United States (in cities such as Denver, Seattle, Atlanta, Austin and Houston) that was through Regal Entertainment Group's Regal Cinemas, Edwards Theatres and United Artists Theatres as part of a “Kidtoon Films” family matinées promotion and it was only shown on weekends.
In Japan, the movie grossed ¥0.9 billion ($10 million USD) and was considered a box-office flop against a budget of around ¥3 billion ($35 million USD).
In the United States, the movie flopped at the box office, only grossed $407,695 during its opening weekend and $1,368,000 domestically.
Hemdale Communications President Eric Parkinson designed a clever home video marketing campaign that enabled the “Little Nemo” video to debut as the nation's number one top selling video with sales of over two million copies.
“Little Nemo” received mixed to positive reviews from critics.
Roger Ebert gave it 2 out of 4 stars, but on a positive note, he wrote that "Little Nemo is an interesting if not a great film, with some jolly characters, some cheerful songs, and some visual surprises."
Peter Gilstrap of the Washington Post wrote in his review: “While not on the level of "The Jungle Book," "Nemo" is 105 minutes of Ninja-free fun sure to please content-worried parents and keep their fidgety spawn glued to their seats.”
Stephen Holden of the New York Times wrote: “Although the film has scenes of combat, its battles have none of the pow, bam and splat of an ordinary cartoon.”
TV Guide gave the film a two star rating, saying: “Despite all the effort, time and energy lavished on Little Nemo: Adventures in Slumberland” by the excellent talents involved, it is, finally, a disappointment.”
The movie won the "Audience Award" at Amsterdam's 1992 Cinekid Festival and was also nominated for "Best Animated Feature" at the 1993 Annie Awards.