It is quite difficult to find these in this book, but...
The early scene where several characters are Polyjuiced into Harry Potter decoys, including twins Fred and George. Their reaction? "Wow, we're identical!"
From the same scene, Harry's reaction to seeing all his doubles changing their clothes: 'He felt like asking them to show a little more respect for his privacy as they all began stripping off with impunity, clearly much more at ease with displaying his body than they would have been with their own.' Ron exclaiming (in a Shout-Out to a joke made in Half-Blood Prince about Harry's chest), "I knew Ginny was lying about that tattoo," can only be topped by this moment after Bill offers to take Fleur on a thestral: 'Fleur walked over to stand beside him, giving him a sappy, slavish look Harry hoped with all his heart would never appear on his face again.'
Fleur, upon turning into Harry (with the real Harry standing right there): "Bill, don't look at me; I'm 'ideous!"
Hermione's innocent innuendo: "Oh, you look much tastier than Crabbe and Goyle!" and Ron's reaction.
And later still, after George has lost his ear and makes his horrible pun 'I feel saintlike... holey', Fred's reaction: "Pathetic! With the whole wide world of ear-related humor before you, you go for holey?"
During the preparation, when Molly orders Ron to clean his room and he refuses.
Molly: Your brother is getting married in a few days! Ron: And is he getting married in my room? No! So why in the name of Merlin's saggy left— Arthur: Don't argue with your mother.
The drunk relative trying to figure out if Polyjuiced Harry was his son.
Charlie, Hagrid, and another wizard getting drunk and singing about Odo the Wizard.
Aunt Muriel (and how she looks like a "badly-tempered flamingo") and Ron's response to her.
Ron: Nightmare, Muriel is. She used to come 'round every Christmas until, thank God, Fred and George put a Dungbomb under her chair and she took offense. Dad always said she'd write them out of her will.
Hermione trying to kick Ron under the table and hitting Harry instead.
Ron saying about Muriel, "She's rude to everyone" and George comes up saying "Talking about Muriel?" He follows this up with, "She just finished telling me my ears are lopsided."
The descriptions of Ron's uncle and how he celebrated at parties.
Fred: He used to down an entire bottle of firewhisky, then run on to the dance floor, hoist up his robes, and start pulling bunches of flowers out of his—
Luna's ability to instantly recognize Harry despite the polyjuice potion.
When Harry goes upstairs in his house without telling Ron and Hermione when he, Ron and Hermione are hiding there for a bit, they freak out and once Hermione finds Harry and calls out to Ron that she found him, he calls back "Tell him from me he's a git!"
While the school is preparing for the final showdown against Voldemort, Filch comes barreling out of nowhere screaming, "Students out of bed! Students in the corridors!"
To which McGonagall snaps; "They're supposed to be, you blithering idiot!"
Sir Cadogan shouting encouragement to Harry just before the final battle begins.
After Dumbledore tells Snape that he wants Snape to kill him, Snape responds, in full Sarcasm Mode, "Would you like me to do it now? Or would you like a few minutes to compose an epitaph?"
Ron to his daughter, Rose: Thank God you've inherited your mother's brains.
Fleur's transparent attempt to break the tension between the newly-arrived Percy and the rest of the Weasleys by asking Lupin about how Teddy is doing. Lupin catches on and loudly announces that he's got pictures, desperately trying to shove them in everyone's faces.
Kreacher: *after Harry stops him from knocking out Mundungus* One more for luck, Master Harry?
Later, the Trio immediately realizes who Mundungus is talking about when he mentions she "looked a bit like a toad."
Peeves calling Voldemort 'Voldy'.
We did, we bashed em!
Wee Potty's the one!
Now Voldy's gone mouldy, so now let's have fun!
Ron: "Really gives a feel for the scope and tragedy of the whole thing."
The scene when they're about to leave the Dursleys' has some good ones.
Harry: If you think I'm going to let you risk your necks for me—
Xeno: ""Everyone always requets our recipe for Freshwater Plimpy soup."
Ron (under his breath): "Probably to show the Poisoning Department at St. Mungo's."
When reading the fairy tale that tells the origin of the Deathly Hallows.
Hermione: Death has an invisibility cloak?
Ron: Yeah, well, sometimes Death gets tired of running after people, flapping his arms and shrieking...
The gargoyles outside the staffroom get blasted to bits. Doesn't stop them from snarking as Harry rushes past, though.
Gargoyle: Oh, don't mind me...I'll just lie here and crumble....
When the group gets attacked while sitting at a pub, during the fight we look into the kitchen and see the attendent just standing there obliviously enjoying earpiece music while the whole area outside gets trashed.
Harry is searching Umbridge's office and finds a book titled "When Muggles Attack".
Just before going in the elevator, Ron, in disguise recieves some disturbing news. Apparently his wife is in court. He's actually quite worried about it. Until he's reminded...
Harry: Ron, you don't have a wife.
Shortly afterwards, they discuss what happens if they can't find Umbridge, only for the elevator to open with her standing right there.
Ron has been asked to fix an office's water rune, because it is raining inside the office constantly. When he meets Harry again, he is completely drenched.
Later, a new addition that was not used in the book: Ron, as Reginald, tries to leave Mary Cattermole so he can regroup with Harry and Hermione. Before she lets him go, she forces a kiss onto him, unaware that he is in fact Ron. Ron's Polyjuice Potion chooses to wear off at this exact point, and at the same time the real Reginald finds Mary and Ron kissing. Ron then leaves the real Reginald and a very confused Mary to regroup with Harry and Hermione.
Any of the Polyjuice Potion sequences—Harry, Ron, and Hermione looking freaked out in the guise of Ministry employees (one of whom is the normally badass Runcorn) and then Hermione-as-Bellatrix, trying so hard to look dangerous.
Hermione!Bellatrix: [awkwardly] Good morning.
Griphook: [under the Invisibility Cloak] "Good morning? Good morning??" You're supposed to be Bellatrix Lestrange!
"Just keep telling her about that ball of light going into your chest."
After Ron returns to the others and Hermione is angrily stalking after him:
Hermione: Give me my wand, Harry!
Harry, very blatantly pulling his sweater down to hide it as he stuffs it in his pants' waistband: What? I don't have it.
"Hermione, when have any of our plans actually worked? We plan, we get there, all hell breaks loose!"
Neville's reaction during the final battle when Scabior takes that first step across the barrier.
The kiss between Harry and Ginny in Part 1, which was observed by George as he dances into the room with a toothbrush in the hole where his ear used to be. When the two break the kiss and look at him, he gives a sly grin and says "Mornin'."
After getting blasted by Voldemort from the courtyard all the way back into the Great Hall, Neville comes to in the most serene and blissfully unaware way possible, while all hell's breaking loose around him.
When the trio returns to Hogwarts, Harry and Ginny have a Held Gaze moment. While Ron grins and waves in the background, then complains to Hermione about being ignored.
Ron: I just get back and she looks at me like I'm Frankie First-year. I mean, I'm her brother.
Seamus: She's got plenty of those though. There's only one Harry.
Not to mention Hermione's expression during this. She has a moment of 'Hehe, I'm his girlfriend!' before shooting a 'Don't. Say. A. Word' look at Harry.
Harry has an important mission for the D.A.:
Harry: Okay, there's something we need to find, something hidden here in the castle, and it may help us defeat You-Know-Who. Neville: Right, what is it? Harry: We don't know. Dean: Where is it? Harry: We don't know that either. I realize that's not much to go on. Seamus: That's nothing to go on.
There is a moment when Hermione is cutting Harry's hair just as she realizes how to destroy the Horcruxes.