Monsters, Inc. premiered in the United States on October 28, 2001, and went into general release on November 2, 2001 with the best opening ticket sales ever for an animated film and the sixth best of all time.
The story is set in Monstropolis, a city inhabited by monsters who live in deep fear of children which they believe will kill them simply by touching them. Ironically, the city's power comes from the screams of children which are bottled and converted to energy by Monsters Incorporated. "Scarers" work to frighten the children and are regarded as the heroes of Monstropolis for being brave enough to enter a child's room.
The top scarer at Monsters, Inc. is James P. Sullivan, or "Sulley" (John Goodman), a blue-furred bear-like giant who is partnered with the green, one-eyed Mike Wazowski (Billy Crystal); Sulley's main rival is the chameleon-like Randall Boggs (Steve Buscemi). When taking care of paperwork, Sulley discovers a door that has been left on the scare-floor after shift, contrary to strict company policy. When Sulley investigates the door, Boo, a small humangirl, enters the monster world; not only that but he and Mike also learn that the girl is actually a victim of an evilplot to solve the city's power problems. It's up to Sulley and Mike to get her back home before the authorities find out and before the company gets turned upside down. Along the way, they discover that children are not dangerous and that scaring is no longer rewarding. They have numerous encounters with Randall, with the "Scream Extractor", the spider-like head of Monsters, Inc., Mr. Waternoose, and the Abominable Snowman. In the end, they solve their world's energy crisis when they find out that a child's laughter has ten times the power of a scream; thus, all the monsters have a new mission: to sneak into children's rooms at night and make them laugh.
The scene where Sulley fears Boo has been thrown in a garbage compressor is inspired by the 1952Chuck JonescartoonFeed the Kitty.
The garbage compressor (trash compactor) is labeled "XP-13". This is probably a reference to the low budget "chop-job" 1970 sci-fi/horror film "Horror of the Blood Monsters", which carried the tagline: "You'll scream yourself into a state of shock!". In "Horror of the Blood Monsters" the space ship is named the "XP-13".
Some of the "sets" in this film were used in the animated feature Toy Story.
All of the digital displays in Monstropolis (Sulley's clock radio, scare station consoles, "Days Without An Accident" sign) are nixie tubes, a neon digital display technology from the 1960s. The five- and six-digit numbers displayed with nixie tubes near the doors are all birthdays of Pixar employees and/or relatives.
The "scream extractor" is made up of several other props seen earlier in the film.
Near the end of the film, Boo excitedly shows Sulley her toys in her room. One of the toys she hands him is a clownfish, a hint to the 2003 hit Pixar movie Finding Nemo, a ball which was in Luxo Jr, and another is Jessie from Toy Story 2.
The names on the scream-totals board (with the exceptions of Sulley and Randall) are all the names of Pixar employees.
Mary Gibbs, the three year old daughter of writer Rob Gibbs, provided Boo's voice. They were unable to get her to sit still in the recording studio, so instead they followed her around with a boommike, and cut things she said while playing into the movie.
When Mike does his comic turn near the end of the film, he signs off with "Tip your waitresses!", something Mr. Pink in Reservoir Dogs refuses to do. Mr. Pink was played by Steve Buscemi, who also supplied Randall's voice.
When Mike enters the room of a child near the end of the movie you can see early posters of Disneyland attractions and lands.
When Boo sits in the cubicle in the men's room, she sings a couple of verses of the theme song from Beauty and the Beast.
The restaurant Mike visits is named after a famous stop motion director Ray Harryhausen.