- Sulley opens the rebuilt door. "Boo?" "Kitty!". His joyous expression says it all.
Mike: Sorry it took so long, pal. It was a lot of wood to go through.
- Not only that, it was Mike, who started off as a selfish Jerkass, going through all the trouble (and splinters) to rebuild the door in the first place. Now that's friendship. What makes it even sweeter is his apology to Sulley about the time necessary.
- The ending was such a moment of heartwarming, especially Sulley's final smile, that Pixar opted instead to do a prequel as opposed to a sequel, feeling they couldn't bring themselves to continue the story after that perfect moment.
- Any of Sulley and Boo's scenes together, like when he helps her fall asleep by showing her that there's nothing scary in the closet.
- The bathroom scene where he plays "hide-and-seek" with her. This and the example above both show Sully forming a paternal bond with her.
- When Sulley shows up to rescue Boo from the Scream Machine, Boo excitedly exclaims, "Kitty!" and after freeing her, Sulley apologizes for scaring her earlier, saying, "Sorry, Boo." Can you say, "Daaaaawwwww"?
- Mike hugging Boo goodbye.
"Go on. Go... grow up."
- Mike's evolving attitude. Through most of the film, he just wants to get Boo back out of his and Sulley's lives. By the end, he's willing to decoy the CDA to help save her from the bad guys. Whether you believe he did it for her or Sulley (or maybe both) that's a big change.
- Boo's tiny little nod when Sulley reassures her when they're hiding under a desk.
- If I Didn't Have You. It's the Heterosexual Life-Partners song.
- When Sulley declares that "none of it matters anymore", Mike is visibly crushed. You can see Sulley regrets the words almost immediately, but he doesn't take them back. Mike then names several things he feels should matter to Sulley. "What about everything we ever worked for? What about Celia? And what about me?" That last one is when Sulley turns around and apologises - because Mike does matter to him.
- And after that, Mike still somehow makes the same daring venture Sulley does back into Monstropolis — even though his lack of fur means he could easily freeze to death in the Himalayan climate — just to reconcile, adding that it wasn't like he doesn't care about Boo. Yeah, it's juxtaposed by Randall attacking Sulley but it was a cute gesture (and Mike does ultimately save Sulley, even if by accident).
- The conclusion of the film: Seeing the monsters be reassigned from In-Universe Nightmare Fuel to entertaining kids and evoking laughter from them. Because the emotional energy they get doesn't have to be negative. The monsters get the electrical power they need, and the children they visit are made happy; everybody wins!
- Not only that, but studies have shown that laughing at night helps you sleep. No longer will those kids have night terrors. Instead they will be able to sleep a whole lot better now.
- And it looks so much more fun to work in, now.
- Made even better after the prequel. Oozma Kappa had to work hard to overcome their limitations during the "scream power" days. Now they can be the superstars.
- Blink and you'll miss it: when Sulley is trying to console Boo after accidentally scaring her, Mike can be heard in the background trying to convince Waternoose that she's not dangerous, at one point referring to her as "that sweet little girl." A far cry from how he used to talk about her.
- In Bonus Features, the interviewer asked Sulley how he became Monster's Inc's top scarer, he replied that he didn't do it alone, as he has the world's best assistant: Mike Wazowski.
- And in the prequel, it was demonstrated that Mike knew more about scaring that Sulley did even though the former wasn't scary at all. And at the end, it was Mike's brilliance that led them to escape from the Human World. Sulley even pointed out to him that Mike is the one who is the brains of the operation. This ultimately means that in the interview, Sulley wasn't just complimenting Mike, he actually meant it.
- In a odd sort of way, the play (from the bonus features on the DVD) that Mike and Sulley stage. As Stylistic Suck-y and humorous as the play may be, it's still nice to see that the monsters can still have a good laugh at the ordeal even after everything that had just recently happened.
- On the Blu Ray, the filmmakers briefly discuss the effect that 9/11 had on the film's production, from having to reanimate one gag involving a mushroom explosion into a plasma dome to their own self-doubts about whether or not they were doing something worthwhile by making a lighthearted family film while the country was in peril, as well as the doubt that anyone would want to go to the movies sixty days after such devastation. Not only was the movie a huge hit, but viewers shell-shocked by the attack thanked them for releasing a movie about not being afraid of scary things at a time where everyone in the country was so fearful.
- The voice actress for Boo, Mary Gibbs, was about as old as Boo during the time of production. She wouldn't sit still in a recording booth, so the producers had to chase her around Pixar with a microphone as she would randomly play, sing, and babble.