After Jane slaps Loki, watch Sif in the background. First she stays there looking surprised and then turns to Jane with an expression that seems to say, "I wasn't expecting that, but I'm kind of impressed".
Even better, Thor gives Jane a brief 'What the-?' double take, like he can't believe his girlfriend just hit his evil little brother.
Sif threatens to kill Loki, and he only smirks before saying it was nice to see her again. Then, barely minutes later, Volstagg does the same. Loki, obviously reminded of Sif's threat (as well as Thor's earlier threat), can't help but comment, "Evidently, there will be a line."
While being examined in Asgard, Jane asks if she’s in a quantum field generator. The Asgardian medic replies primly that it's a "soul forge". When the medic reluctantly confirms Jane's description of what the soul forge appears to do, Jane turns to Thor with a grin and stage whispers, "Quantum field generator."
Odin arrives, and compares Jane being in Asgard to a goat at a banquet table. Jane is not happy with being compared to a goat.
Jane: Did he just...? Who do you think you are? Odin: I am Odin. King of Asgard. Protector of the Nine Realms. Jane: Oh.
When she realizes that Odin knows exactly who she is, she turns to Thor and asks, "You told your dad about me?"
Before she reunites with Thor, the rain doesn't touch Jane because of the Aether, and because Darcy's standing next to her, the rain's not touching her either. Then Jane sees Thor, moves away... and the rain hits Darcy.
Odin: We are not gods. We're born, we live, we die. Just as humans do. Loki: Give or take five thousand years.
The facetious manner in which Loki clicks his heels together to stand at attention when he reaches Odin's throne.
Birds appear at the feet of Ian, Darcy and Selvig; the latter comments:
Selvig: There's nothing more reasuring than realising the world is crazier than you are.
Then, he throws away his huge bag of meds.
Thor's increasingly frustrated attempts to get the flying ship started by punching random buttons. Loki tries to get him to go about it logically, and Thor's response is to hit the controls harder.
And it works.
When Thor and Loki are escaping from Asgard in said flying ship:
Loki: I think you missed a column. Thor: Shut up. [they fly their ship out of the hall they've just wrecked] Loki: Look, why don't you let me take over, I'm clearly the best pilot! Thor: Is that right? Out of the two of us, which one can actually fly? [various aerial acrobatics ensue, and Thor manages to knock the top off a tower] Thor: Not a word. [pursuit is fast approaching] Loki: Now they're following us. [shots] Now they're firing at us! Thor: Yes, thank you for the commentary, Loki, it's not at all distracting! [they enter a tunnel, the wing of the craft accidentally cutting the head off one of the statues outside it] Loki: Well done! You just decapitated your grandfather.
Jane faints halfway through, and Loki says, in the most bored tone ever, "Oh dear, is she dead?"
Loki starts yelling at Thor, pointing out all the flaws to his plan; specifically, how bad an idea it was to steal a large and obvious ship in order to escape. Thor's response is... to push him out of the hatch. Then he grabs Jane and jumps out after him, where Fandral is waiting with an Asgardian boat.
And when Loki realizes that Thor lied to him about it:
Thor on the London Underground. "How do I get to Greenwich?" (This is even funnier for Londoners since the answer given is impossible).
The lady he asks barely blinks at his appearance when she answers. This is followed by her bumping against Thor clearly on purpose and clearly just for the chance to, much like Agent Carter to Steve Rogers, sneak a grab at his heroic pecs. And judging by his expression, he knows, and thinks it's funny.
Another passenger on the train also takes the opportunity to pull out her camera phone.
Loki being damn near giddy with delight immediately after Thor releases him from prison.
Loki: This is so unlike you, brother! It's very... clandestine! Are you sure you don't want to just punch your way out? Thor: If you keep talking, I might.
Loki makes use of his illusionary powers by turning Thor into Sif, and afterwards turning himself into Captain America. Who he then proceeds to thoroughly take the mickey out of. Even the hilariously cheesy music from the WW2 presentation makes a return.Chris Evans manages to nail a lot of Hiddleston's mannerisms and inflection in his performance.
Loki: [after turning Thor into Sif] Oh brother, you look ravishing. Thor: [with his normal voice] It will not hurt any less when I kill you in this form. Loki: Perhaps you prefer one of your new companions, given that you seem to like them so much. [turns into Captain America] Oh, this is much better. The costume is a bit much, so tight... but the confidence! I can feel the righteousness surging! Hey, want to have a rousing discussion about truth? Honor? Patriotism? God bless Am--! [Thor clamps a hand over his mouth to avoid being overheard by a guard]
And then, when Loki asks for his daggers back, Thor appears to give them to him... but then Loki stops smirking, holds up his hands and reveals that Thor actually handcuffed him. Thor's grin is priceless.
Thor: I thought you liked tricks?
Erik Selvig running around Stonehenge naked.
Possibly the biggest laugh of the entire movie: When Jane and Thor arrive back on Earth, Thor turns to look at the coat hangers... before hanging his hammer on one. Since his hammer doesn't rip it off the wall, we can assume that they were very worthy coat hangers.
Erik greets them happily, in a shirt and tie... and his underwear. According to Ian, it helps him think better.
Before they go out to save the day: "I'd better go get my pants."
Erik: Your brother's not coming, is he? Thor: Loki's dead. Erik: Oh, thank God! Thor: ... Erik: I mean...I'm so sorry for your loss.
A literal Brick Joke: when the group discover the portals, they throw a brick into one of them, and it doesn't come back. Then later, when Jane wakes up from being unconscious, the brick appears of out nowhere and lands in the background.
Ian ends up throwing something into them... which don't come back. Darcy asks flatly, "Were those the car keys?" They were.
Another Brick Joke: Darcy asks for one of Jane's shoes to throw in, and after Jane wanders off she asks Ian for one of his. Later, when Thor and Jane are in the cave, Thor asks, "Why are there so many shoes in here?"
While most of the scene is a Tear Jerker, there's this after Thor and Loki stop fighting after an argument concerning Frigga:
Thor: She wouldn't want us to fight. Loki: ...Well, she wouldn't exactly be shocked.
During the prison break, Thor arrives and announces that he can guarantee their safety if they surrender. One creature attacks him... and Thor immediately takes back his words before hitting him.
Thor: Lay down your arms and return to your cells. You have my word, no harm will come to you. (Marauder punches him) Very well, you do not have my word.
A bit earlier, Fandral reacts to the news of the riot:
Fandral: It's as if they resent being imprisoned!
And what's Loki doing during said prison break? Calmly reading (and looking mildly annoyed about the noise of the battle outside his cell).
During the final battle, portals start opening up everywhere. Thor and Malekith end up in several realms, Darcy and Ian end up all over London…
Two fighter jets make an unintentional visit to Vanaheim when attempting to fire missiles at the Dark Elves' space ship. They manage to return to Midgard just after the final battle none the worse for wear.
Thor and Malekith land on London's Gherkin and both slide face-first (with classic sound effects) down the glass. The people inside can only watch in confusion. They even try to reach for the glass to save themselves, because without Mjolnir, neither of them can fly.
This might be a Shout-Out to Adventures in Babysitting, in which a Thor-obsessed girl named Sarah slides down a similarly transparent skyscraper in Chicago—nice bonus for that film's fans.
Jane and Erik try to evacuate the naval college, but everyone is just watching the battle:
Jane: What are you all doing? You need to get out of here! Now! Bystander: You're joking, right? That's Thor out there! He's waving his hammer around and everything!
After Ian saves Darcy, a portal transports them to Erik and Jane... while they're locked in a passionate kiss. With, just to be clear, Darcy dipping Ian.
Jane: Darcy?! Darcy: [surprised, she drops Ian] Jane?! Eric: [disbelief] Ian?! Ian: [embarrassed] Mr Selvig?! Darcy: [as Mjolnir rockets past the group looking for Thor]Myeh-Myeh?
Speaking of which, Mjolnir whizzing around, trying to find Thor. It's like a dog running through the house looking for its master's voice, and getting rather irritated over it.
Thor and Jane share a moment in a cave... and then Jane's phone starts ringing with its gangsta rap ringtone.
To add insult to injury, it's Richard calling her. Thor's changing facial expressions while she's talking to him are priceless. Once they're going again, he asks, "Who's Richard?" Jane's reaction is just as priceless.