Corrected entry: In the opening scene, when the monster falls on the jacks, we see the door is less than half open. When the video is replayed, we see that the door is left more than half way open. (00:02:45 - 00:03:45)
Corrected entry: In the computer animation process, they make certain set pieces which can be used over and over again - when mike is being threatened with the 'scream remover' you can see that it is made up of canisters for screams, and various other parts, including half a door sorting frame for the main arm
Corrected entry: When Mike and Sully are at the lockers and Mike puts in his contact, Randall slams Mike's locker, and that should have locked it, but Mike re-opens it with out re-entering the combination (00:10:55)
Corrected entry: When Sully and Mike first speak to the geeky monsters in the lobby, you can see a slug-like monster in the background just entering one of the corridors leading to the scarefloors. When Mike is talking to Celia a short time later, the same slug still has yet to enter the corridor.
Corrected entry: When Sully and Mike go back to work to take Boo back to her home, the clock on the wall as they enter says 8:50, a few minutes later Boo takes off and Mike and Sully go after her, a few minutes later Randell catches Mike and points to the clock which now reads 11:55. The chase only lasted a few minutes.
Corrected entry: The chef at Harryhausen's has a bandana with a Japanese symbol on it, and throughout the entire restaurant scene the symbol on the bandana changes.
Corrected entry: Just after the door is shredded, Mr. Waternoose or his assistant says something like "That's 56 doors this week. Kids just don't scare like they used to." 56 doors in a week is nothing when you consider that a kid is born roughly every 3 seconds - that works out at around 201,600 doors every week. Shredding 56 doors still leaves them with 201544 doors, which seems a lot more doors than they have monsters.
Corrected entry: Just before they go into the scare room, a slug looking monster is mopping up a spill. When he is done, he leaves his own trail of sludge. When we see all of the scarers walking to their doors a little later, the slug is there, but the floor behind him stays clean.
Corrected entry: The Abominable Snowman tells Mike and Sully that the Himalayan village is 'a three day hike' down the mountain. However, after about two minutes of sledding/tumbling, Sully gets to within what looks to be less than a half-mile from it. Even more inexplicable, Mike was pretty much right behind him, judging by how quickly he finds Sully back at the factory.
Corrected entry: The scare total display board on the scarefloor wall shows the scarers with their photo and last name. There is one mistake. Randall's last name is Boggs but the display board says Randall.
Corrected entry: All the toilets in the Monsters Inc. men's room are in the size and shape familiar to us as being for human use. Yet only three or four of the monsters are close enough to humanoid form that would make the toilets accessible for sitting.
Corrected entry: When Sully and Waternoose are talking, Waternoose pours himself a cup of coffee. Just after Waternoose takes a sip, Sully demonstrates his scaring ability on him and he drops his cup. The sound we hear is of an empty cup hitting the floor, but didn't Waternoose just fill it with coffee? There should have been a splash type noise to indicate the coffee has spilt on the floor.
Corrected entry: When Boo is first discovered by Mike & Sully, they refer to Boo as 'it' and 'the child'. During the bathroom scene when Sully tells Mike that he named the child Boo, his exact words are "That's what I named her". There is no explanation why he switched the pronoun from 'it' to 'her'. For the rest of the movie, they do refer to Boo as 'her'.
Corrected entry: When Sully and Mike leave the company bathroom, they are walking down the hall and you can see that both of Mike's legs are wet. As they keep walking down the hall, they dry far too quickly.