From the book:
- Among Harry's unconscious usages of magic, there is the time when he turned the wig of a teacher blue and the time when Aunt Petunia wanted to force a particularly ugly sweater of Dudley's on him, and as she was trying to put it on Harry, the sweater started to shrink smaller and smaller until it would have perhaps fit a baby or dog but not him. Fortunately, she decided it must have shrunk in the wash, so Harry wasn't punished that time.
- Towards the beginning, Dudley tells Harry that they stuff people's heads down the toilet on the first day of Stonewall High and asks him if he wants to practice. Harry's response is 'No thanks, the poor toilet's never had anything as horrible as your head down it - it might be sick," and then runs away before Dudley can work out what he said.
- A small one from Dudley, regarding the Hogwarts letters (also notable as it's probably his most civil moment with Harry in the first book):
"Who on Earth wants to talk to you this badly?"
- Concerning the Hogwarts letters - McGonagall sent those letters - McGonagall is responsible for flooding the Dursleys house with letters! She also hid them inside eggs. This is the child of her best students, students she adored; he's coming to Hogwarts, whether the Dursleys like it or not.
- "While he drove, Uncle Vernon complained to Aunt Petunia. He liked to complain about things: people at work, Harry, the council, Harry, the bank, and Harry were just a few of his favorite subjects. This morning, it was motorcycles."
- "MOTORCYCLES DON'T FLY!" (for context, Vernon says this line after Harry mentions that he dreamt about a flying motorcycle.)
- From the Stephen Fry audiobook, the sound he makes when Harry steps on Vernon's face as he's camping by the front door.
- "Uncle Vernon made another funny noise, like a mouse being trodden on."
- Doubles as Hilarious in Hindsight, but early in the book when Vernon is intimidated by Hagrid he whimpers something that sounds like "Mimblewimble". Guess what? It's an actual spell.
- It's a small one, but nonetheless the scene where Hagrid is in Gringotts and reaches into his pocket to find Harry's key only to come up with a bunch of dog biscuits counts.
- Made even funnier when you realise that those biscuits are meant for Fluffy; i.e., a giant three-headed monster dog.
- Or for Fang, his normal dog...
- Harry, on the "last day of August" (31 August) finally bites the bullet and asks Uncle Vernon if they can take him to King's Cross the next day so he can catch his train to Hogwarts. Vernon begrudgingly agrees, citing that they had to go to London anyway to get "(Dudley's) ruddy tail removed before he goes to Smeltings." Now, keep in mind when Dudley got that tail in the first place - when Hagrid first appeared and Vernon made the mistake of pushing Hagrid's Berserk Button. All this was back on Harry's eleventh birthday - 31 July - which means that at this point Dudley's been walking around with a pig's tail growing out of his bum for a month.
- Vocabulary lessons with Hagrid:
Harry: I never know, what's the difference between a stalagmite and a stalactite?
Hagrid: "Stalagmite's" got an 'M' in it.
- The Weasley twins at the beginning.
"Don't cry, Ginny. We'll send you loads of owls."
"We'll send you a Hogwarts toilet seat!"
"Only joking, Mum."
- Even funnier is that it's a callback to an earlier funny moment. Mrs. Weasley makes it clear that she wants the twins to behave this year, leading to her warning them "If I get one owl that you've... blown up a toilet or something..." This cues them to respond that they've never done that before, and are grateful for the suggestion.
- And then when Harry is in the hospital wing, they try to send him a toilet seat.
Dumbledore: "I believe your friends Misters Fred and George Weasley were responsible for trying to send you a lavatory seat. No doubt they thought it would amuse you. Madam Pomfrey, however, thought it might not be very hygienic, and confiscated it."
- Dumbledore's Chocolate Frog card: "Professor Dumbledore enjoys chamber music and ten pin bowling." Best. Mental. Image. Ever.
- After Ron meets Hermione for the first time, he comments, "Whatever House I'm in, I hope she's not in it." Of course, not only does Hermione end up in Gryffindor with him, but the epilogue in the seventh book reveals that she eventually becomes his wife, meaning that Ron will live in the same house as Hermione for the rest of their lives!
- Dumbledore's pre-banquet speech:
"Welcome! Welcome to a new year at Hogwarts! Before we begin our banquet, I would like to say a few words. And here they are: Nitwit! Blubber! Oddment! Tweak!
Thank you!" (Since the words would be "Silly one! Fat one! Loser! Braggart!" it is Fridge Logic too.)
- Harry's reaction is quite good as well.
- Jim Dale singing "Hoggy Warty Hogwarts" for the audiobook of Philosopher's Stone.
- Malfoy bragging about how skilled at flying he is at the beginning of chapter 9, telling "long, boastful stories which always seemed to end with him narrowly escaping Muggles in helicopters."
- Another darkly humorous bit about this: Given what we find out about him not much later into the series, where the hell did insular, pure-blood supremacist Draco Malfoy find out about helicopters (even Muggle-curious Arthur Weasley had no idea how the underground worked), let alone get it into his head that stories where he was escaping from them would impress his wizard classmates? Did he somehow sneak some sort of Muggle action movie as a little kid and then get caught out by his parents like, "No, Draco, Muggles are a lesser breed of human, remember?"
- Realizing that Fred and George jinxed snowballs to hit Quirrell's turban, and that they were unknowingly smacking Voldemort in the face!! You can just imagine Voldemort under the turban going "don't blow your cover, don't blow your cover, don't blow your" *SMACK*
- When Harry gets the idea to have Charlie Weasley take Norbert off of their hands, he first launches the idea by glancing at Ron and muttering "Charlie". Ron's response?
"Now you're losing it too. I'm Ron, remember?"
- After Hagrid tells Harry and Hermione that he's given Norbert a teddy bear:
From inside the crate came ripping noises that sounded to Harry as though the teddy was having his head torn off.
- Harry tells Ron and Hermione that Snape is going to be the referee for the following match.
Hermione: Don't play.
Ron: Say you're ill.
Hermione: Pretend to break your leg.
- When we first meet the centaurs, they all comment that "Mars is bright, tonight" with Hagrid getting more and more annoyed.
"Mars is bright tonight."
- After dropping through the trapdoor Fluffy was guarding, Harry and Ron find themselves trapped by some Devil's Snare. Hermione tries to remember how to fight it:
"Devils Snare, Devils Snare... what did Professor Sprout say? it likes the dark and the damp "
"So light a fire!" Harry choked.
"Yes of course but theres no wood!" Hermione cried, wringing her hands.
"Lucky you pay attention in Herbology, Hermione," said Harry as he joined her by the wall, wiping sweat off his face.
"Yeah," said Ron, "and lucky Harry doesn't lose his head in a crisis — 'there's no wood', honestly."
- The book specifically mentions Hermione's skill at conjuring her bluebell flames, which she uses at least twice before (most notably to set Snape on fire during the Quidditch match).
- More from the hospital wing scene:
- "What happened between you and Professor Quirrell down in the dungeon is a complete secret, so, naturally, the whole school knows."
- Dumbledore trying Bertie Bott's Every-Flavour Beans.
- He originally lost his taste for them after an unfortunate encounter with a vomit-flavored one, but thought he'd "be safe with this toffee-flavored one".
From the film:
"Eye of rabbit, harp string hum, turn this water into rum!"
- When Hagrid knocks the door off its hinges: "Sorry 'bout that!"
- And he does it in the most casual tone possible.
- And then he fixes the door just by standing it back up.
- Also when he's accidentally telling them loads of information about the Stone. "I shouldn'ta told you that! I should not have told you that!"
- Dudley being mistaken for Harry and having to tell Hagrid that he's not Harry becomes hilarious when you find out that his actor's first name is Harry.
- During the somewhat-tense verbal exchange between Hagrid and the Dursleys and Hagrid calls Vernon a Muggle, Harry asks what a Muggle is, and Hagrid offhandedly tells him "Non-magic folk" before shifting attention back to Vernon.
- In a deleted scene, Hagrid confirming for Harry that the gloves he needs for school are indeed made of dragon-hide:
Harry: 'One pair of dragon-hide gloves.' Hagrid, do they mean from a real dragon?
Hagrid: Well, they don't mean a penguin, do they?
- When Dumbledore announces that the third-floor corridor is out-of-bounds to anyone who "does not wish to die a most painful death" (and does so in the same businesslike way he handles all of the other announcements), the other students whisper amongst each other in curiosity. Meanwhile, Harry's face is pure WTF. It's #1 on this list.
- Before McGonagall can even place the Sorting Hat on Malfoy's head, it shouts "SLYTHERIN!" with no hesitation.
- The Hat's reaction to being put on Ron's head too.
Sorting Hat: HA! (Ron is startled by the sudden noise) Another Weasley! I know just what to do with you! GRYFFINDOR!
- Hermione's reaction to Harry and Ron arriving late to Transfiguration.
- McGonagall's reaction to them arriving late. I bet she's thinking: "Oh, I am a cat and they are late! I love this! Transform!"
- Ron Tempting Fate with his comments: "Can you imagine the look on old McGonagall's face if we were late?" and then switching directly to ass-kissing mode after she transforms. Then McGonagall's snarky comment in reply.
- Also, was she just sitting there in Beast mode when all of the students walked in? These are first years, of course, so many of them would have never seen an Animagus before. A lot of them (particularly Muggleborns or those who, like Harry, may have been Raised By Muggles) likely didn't even know an Animagus was a thing. They just walked into the classroom looking for their Witch Classic of a teacher and saw a freaking cat just sitting casually on the table. Think about that for a second.
- Rupert Grint's delivery of the way he mimics Hermione after Charms class. Done much better than in the book.
"It's Levi-OOOOOOHHH-sa, not Levio-SAAH"
- And from the same scene, Seamus establishes his distinctive Running Gag.
Seamus: Wingard Leviosa, Wingard Leviosa, Wingard
Harry: ...I think we're going to need another feather over here, professor.
- In his first Potions class, Harry dutifully takes notes on Snape's introductory spiel:
Bewitch the mind
Ensnare the senses
Put a stopper in death
- During the flying lesson, Ron's broom springs up and baps him right in the face. Even Harry and Neville can't help laughing at him. If you pause at the right time, Ron looks like he's going to laugh when he says "Shut up, Harry."
- Hermione during the flying lesson, when Harry persists in chasing after Malfoy: "What. An. Idiot."
- Hermione's reaction when Harry says "Up" and his broom jumps into his hand immediately.
- "Troll in the dungeon!" scene. Especially the terror-stricken look on Malfoy's face.
- Emma Watson's delivery of the "killed, or worse, expelled" line.
- Ron's response to that line:
*Harry nods in serious agreement*
- In the otherwise intense scene where Harry runs into Quirrellmort drinking unicorn blood and tries to run away, you can see Malfoy and Fang running around screaming in the background.
- Quirrell: TROOOOLL! IN THE DUNGEOOOON! TROLL IN THE DUNGEON! (beat) thought you oughta know. (fainted)
- And when all the students promptly panic, Dumbledore shuts them up.
- At the table, Seamus is trying to turn his water into rum by saying a little rhyme. Eventually, it explodes instead, leaving him with an Ash Face.
- Hagrid worrying about Norbert after he's been sent to a colony in Romania. Filch has no sympathy.
Hagrid: What if he don't like Romania? What if the other dragons are mean to him? He's only a baby, after all.
Filch: Ah, for god's sake, pull yourself together, man.
- When Malfoy starts protesting against, Filch looks at him with this expression of utter disbelief.
- Sadly it wasn't in the film itself and only in the script, but this small conversation between McGonagall and Ron talking about Snape near the end of the film, after McGonagall tells Harry that his father saved Snape's life once:
McGonagall: (to Harry) I suppose he felt it his... obligation... to look after you this year.
Ron: Of course! And now that he's squared things, he can hate Harry in peace, right, Professor?
McGonagall: Hogwarts teachers do not hate their students, Mr. Weasley... (pointedly, as she exits) No matter how taxing they may be.
Ron: I think she's warming up to me.