Well I think Wikipedia means when Sully sees the eye from Boo’s costume in the compactor. I went through it frame-by-frame in iTunes, and all I can see is when Sully run down the stairs, the floor number is 13, but I can’t find ‘A1’ anywhere.
Pixar can be clever in how they extend the “A113” rule. Like in the Incredibles, it’s the section Bob is in, when Helen looks in a monitor station, it first starts if I recall…with A1 on the left, and the camera pans to the right to reveal 13 being the floor/section, what have you, that Bob’s on. So A113 would be in the same area/shot, but not neccessarily all together.
A113 was the classroom that two of the animators were in in college. It’s in every PIXAR movie
a113 is a reference to the college room most of the animators learned their skills. i think it was called California institute of art or something. it appears in every pixar film.
in monsters inc it appears on one of the office doors in the hallway sulley and boo run down and bump into the disinfectors
in toy story it appears on a licience plate
in bugs life it appears on the circus crews truck
in finding nemo its on the divers goggles
i cant remember the others
i heard this on a pixar documentary. hope this helps!
Just to clarify, I’ve found out myself that what a lot of people think is A113 on the sign next to the door is actually “B. Brute”, which was pointed out by Pete Doctor back on the DVD commentary.
I have been wondering about this myself cause I was working on a video guide a few months ago for Pixar’s in-jokes, and I feel like it would be incomplete if we didn’t know where A113 was in Monsters Inc. Has anyone ever asked Lee Unkrich on Twitter if it’s in the film or not? I’m sure he would know.
Just found this - “- Sign seen in the background when Sulley sees Smitty and Needleman loading the trash compactor.”
And this:
For anyone who still cares about wanting to figure this mystery out, I just contacted Lee Unkrich on Twitter yesterday asking him about it, and this is what he had to say:
“I think it’s the warning code when George Sanderson brings the sock in on his back. It’s been a while – I’d have to check.”
[url]http://twitter.com/leeunkrich/status/37390829140189184[/url]
I wasn’t going to say this to him but apparently he forgot all about the “2319” gag, which is hard to believe since he was both co-director and editor on Monsters, Inc., not to mention that it was such a memorable recurring line throughout the whole film. Then again, I do know how busy he was making Toy Story 3 and it really was a long time since they made Monsters, Inc., so I’m sure it’s possible that even he would forget every in-joke they were doing at the time. But hey, he said he’d check so that’s a start anyway.
I came pretty close to spotting it as a number on the wall in the door/roller-coaster chase, but it was only “A13” 
so sad
Forgot the one, perhaps?
Think you can post a screenshot of that?
Yep. Very good find.
A113 is on one of the doors as they are running down the corridor on Monsters Inc
It it very common for creators to forget details about their works. Probably they have so many ideas that they forget some.
Pixar is not the only one using A113 as an in-joke or tribute, although they do seem more enthusiastic about it than anyone else. It also shows up in many other movies, and from what I have read a few novels, too.
Yes, it’s been around since 1993, if I remember correctly.
That’s two years before Toy Story.
I think a South Park episode used A113 once.
Yes, I’ve seen them listed among those who’ve used it.
I also saw it in Mission Impossible: Ghost Protocol directed by Brad Bird. when i saw the scene i got a big smile on my face!
Ghost Protocol used it twice. Which one did you spot?
The one i spotted in the movie was the ring with A113 on the side! it’s i while ago so i think i forgot about the other one (or i didn’t spot it haha)can you help me remember?