After the chaotic battle in the Helicarrier in which Loki kills Coulson and escapes, Fury talks to Steve and Tony about what he really wanted out of the Avengers.
A lot of the scenes after that first Helicarrier battle qualify, especially after Barton wakes up from his enchantment, realizing he has killed fellow agents, and then discusses with Black Widow their experiences. She doesn't say much, but their entire relationship is established as he understands exactly what she means with what little she says. Considering the relationship they are supposed to have in the movie, the fact that they only have about three scenes alone, two of them being action, this solidifies everything we've been told about them up until now.
Achilles in His Tent: Both Natasha and Bruce have this to some degree: Natasha is working with Fury to manipulate the rest of the Avengers to S.H.I.E.L.D.'s ends and rebuffs all meaningful contact and collaboration with them, while Bruce adamantly refuses to do anything other than lend his scientific expertise to help S.H.I.E.L.D. track the tesseract. Both of them have changes of heart later in the film.
Hawkeye (in his first major film role) spends the entire first half of the move Brainwashed and Crazy under Loki's spell. In her conversation with Loki, Black Widow's dark past is alluded to (with references to someone's daughter and a hospital fire which suggest her past was very dark). Both of these could be homages to the fact that in the comics, both Hawkeye and Black Widow started out as villians (they were even partnered together!) before undergoing seperate Heel Face Turns.
Nick Fury is played by Samuel L. Jackson. His 616 counterpart is an old white guy, but the Ultimate Universe gave him a Race Lift and later artists drew him to resemble Jackson. In fact, they specifically asked for likeness rights from Jackson for the comic which he grantednote One of the requests that he made in order to use his likeness was to portray Nick Fury in any movie adaptation, which made his later casting as Fury a no-brainer.
Captain America's costume resembles his Ultimate counterpart's, but he acts like the original 616 character.
Thor's costume takes elements from the Ultimate line, his original costume, and his contemporary comic book outfit.
The team is formed by S.H.I.E.L.D. (The Ultimates) in response to a threat by Loki (616) and the Chitauri (back to The Ultimates).
Also, Doctor Banner, in all his slightly snarky, but still clearly shaken by authority glory. He keeps his head constantly averted from anyone with a gun or in a uniform and only becomes comfortable once he's in his lab. Notable especially, in the scene where he and Cap are first exploring the Helicarrier, he sees guards on the door and inconspicuously turns back around like they're going to lock him up if he so much as looks at them wrong.
Aesop Amnesia: Thor's character growth in his own movie mainly focused on him becoming less hot-headed and violent. His first scene here suggests he forgot about that. (Especially egregious given that he doesn't know anything about Cap's and Iron Man's equipment and so would have no reason to expect that a single blow from his hammer wouldn't kill them instantly.)note Of course, given the ending of said movie, he's just found out the brother he loves in spite of everything he's done has come back from falling into oblivion and Cap and Iron Man are apparently kidnapping him.
The Aesthetics of Technology: Asgard and Chitauri weaponry/engineering tends toward the sleek and shiny, while modern human technology favors functionality, though with clear embellishments like Cap's uniform and shield and the Iron Man armors. Form does not, however, follow function, as S.H.I.E.L.D. shows with their boxy, gunmetal-black "Thorbuster" gun based on the remains of the Destroyer, an Asgard weapon.
When the old man in Stuttgart refuses to kneel to Loki, Loki prepares to kill him and calls upon the assembled to "Look to your elder; let him be your example." However, it gets two whole new interpretations when Captain America drops in to deflect the blast. The first is the more obvious, which is to do the right thing regardless of whether you have any hope of survival. The second is an amusing twist, as Captain America is both an exemplar of goodness and technically older than everyone present (except Loki).
Or alternatively, the aesop behind having Captain America defend a German, considering he spent the last time killing Nazis. Oh, and said German clearly showing the backbone the Nazi supporters lacked. Especially poignant when you consider that the old man may have been old enough to remember parts of World War II himself, and see Loki as the same. This interpretation makes the old man's "There will always be men like you" comment especially thought-provoking, and arguably a Crowning Moment of Awesome.
AM/FM Characterization: Tony Stark hacks the PA system to blare AC/DC as he arrives in Germany, showing his need to create a spectacle wherever he goes.
And I Must Scream: Hawkeye's description of what it's like to be brainwashed by Loki. "You ever had someone take your brain and play? Pull you out, stick something else inside? Do you know what it feels like to be unmade?" Natasha, who started training as a child, looks away and says, "You know I do."
Androcles Lion: Tony's kindness towards Bruce and acceptance of the Hulk pays off when the Hulk saves his life at the film's end.
Loki: I won't touch Barton. Not until I make him kill you, slowly, intimately, in every way he knows you fear. And then he’ll wake just long enough to see his good work. And when he screams, I’ll split his skull.
And Your Reward Is Edible: Blink and you miss this gem in the Helicarrier lab between Stark and Banner. Banner brings up Loki's earlier words ("a warm light for all mankind") and guesses correctly that this was aimed at Stark. Tony holds his bag of blueberries out for Bruce, as if that is his prize for getting the answer right. The gesture has clear overtones of tossing a treat to a pet (maybe to the Hulk inside Banner?) after doing a trick, which Bruce obviously gets, since he hesitates before taking a blueberry. (Rogers refuses one moments later, but then again he disapproves of the seemingly flippant way Stark is treating the whole situation and Dr. Banner as well. Accepting the blueberry symbolically puts Banner on Stark's side.)
This was all ad-libbed. Robert Downey Jr. was hungry, and pulled out a snack. Everyone just ran with it.
Anti-Air: Hulk's response to the pilot who tries to eject from the jet.
Anti-Hero: The Avengers are all over the sliding scale.
Bruce Banner is a Type I — he's a meek scientist who just wants to be left alone, but willing to risk his freedom and being put in SHIELD's cage to help protect the world. The Hulk starts as a Type IV, not hesitating to kill anyone who tries to put him in a cage, or worse, but still avoiding innocent people, and ends up as a Type III, a textbook example of Destructive Savior, and not hesitating to beat the Chitauri to death, but still willing to help humans, even those who tried to put him in a cage.
Tony Stark and Thor are both Type II — they're snarky, arrogant, and mostly involved with the conflict for their own reasons (Tony because of his ego, Thor to retrieve his adoptive brother), but the former is a Jerk with a Heart of Gold and the latter is a Spoiled Sweet who comes around to being a team player easily enough.
Hawkeye (when he's not under Loki's control, anyway) is a Type III or IV, depending on the situation he's in. If he's spotting, he's perfectly cool and collected, but get him out on the battlefield and he's lethal.
Black Widow is all over the scale herself, formerly a Type V before she came to meet Clint Barton, she works as a Type IV spy for S.H.I.E.L.D, and ends up being more of an Extreme Type III by the time the movie ends.
Averted with Captain America. He's the only one who's a straight-up hero. Though even there he's still killing bad guys, something most capes would sneer at, though unlike everyone else, he only kills when necessary, and most of the time when he fights he'll land KO punches rather than shoot them. This actually doesn't make him any better a team player than anyone else early on, due to his problems dealing with the numerous Anti-heroes on his team.
Nick Fury, much like the other members of S.H.I.E.L.D., is a Type V that may have slid down to a type IV by the end of the movie. He's a Manipulative Bastard that keeps secrets from the team and tried to use alien tech to build a WMD, but ultimately he just wants to protect the Earth.
Ascended Meme: Science Bros, a name fans used to describe Bruce and Tony, is now the subtitle for the second volume of the Avengers Assemble comic, which features the two, and others. Given that its writer is on Tumblr, this makes sense.
Asskicking Equals Authority: Played for laughs during the Final Battle. The NYPD won't listen to Cap's orders to evacuate the civilians and set up a perimeter until Cap takes out a couple of Chitauri in front of the officers, at which point the the Sergeant there starts giving his men the exact same orders Cap gave a second ago.
Asskicking Pose: The entire team as they stand prepared to fight against the enemy.
Black Widow has "red in her ledger" (i.e. a debt to pay, but also These Hands Have Killed) that she wants to wipe out.
Hawkeye also shows some shades of this. After being freed from Loki's brainwashing, the first thing he wants to know is how many of their fellow agents he's killed while under Loki's control.
Though not overly prevalent in this installment of the universe, Tony Stark's role as Iron Man and his participating in the battle at all can all be attributed to him trying to make up for all the years that he manufactured weapons and that Obadiah Stane was selling them under the table to terrorist organizations.
Attack Backfire: Thor's lightning strike against Tony supercharges the Iron Man suit's power to 475%.
Author Tract: Averted with writer/director Joss Whedon having newly awake Steve Rogers (Captain America) giving his views (which were Whedon's own) on what was wrong with modern society, then cutting the scene out himself due to pacing. Joss Whedon:
"One of the best scenes that I wrote was the beautiful and poignant scene between Steve and Peggy [Carter] that takes place in the present. And I was the one who was like, Guys, we need to lose this. It was killing the rhythm of the thing. And we did have a lot of Cap, because he really was the in for me. I really do feel a sense of loss about what’s happening in our culture, loss of the idea of community, loss of health care and welfare and all sorts of things. I was spending a lot of time having him say it, and then I cut that."
Autobots, Rock Out!: Invoked. When Iron Man arrives in Stuttgart to back up Captain America, he first hacks the nearest sound system — the PA system of Black Widow's quinjet — to blast AC/DC's "Shoot to Thrill" during the fight. This also serves as a Call Back to Iron Man 2, where he enters the Stark Expo with the same song.
Avengers Assemble: Naturally. Though the line itself is only used in a begrudging sarcastic tone by Stark, as seen in the preview. Used as the actual title of the movie in the UK and the Republic of Ireland.
Awesome Anachronistic Apparel: Steve still dresses and wears his hair like he's in the 1940s. Lampshaded when Steve worries that a jaded public might not receive his star-spangled, patriotic uniform as well as the World War II generation, worrying that it might be seen as old-fashioned, to which Agent Coulson assures him that "Maybe we need some old-fashioned."
Awesome, yet Impractical: The S.H.I.E.L.D. helicarrier. Banner even lampshades it. It takes tons of Tony Stark's arc reactor technology to keep it afloat and is likely astronomically expensive. And if two of the turbines are taken out, you have a Colony Drop on your hands.
Ax-Crazy: Crossed with Came Back Wrong. According to Tom Hiddleston, Loki's unprotected fall through the cosmos has led him to "see things". He's forsaken his family and is determined to destroy the Earth and hand the Tesseract over to those who would use its power to subjugate the entire universe just to spite his brother.
Back-to-Back Badasses: Cap and Thor, Cap and Iron Man, Cap and Black Widow, Black Widow and Hawkeye, Thor and the Hulk... it's a popular tactic. The shot of all of them in a circle during the climax is a Money Shot featured in the trailer.
Stark: You're missing the point — there's no throne, there is no version of this where you come out on top. Maybe your army comes, and maybe it's too much for us, but it's all on you... 'Cause if we can't protect the Earth, you can be damn well sure we'll avenge it.
At the end, Nick Fury suggests that he orchestrated much of what happened in the film as a big Badass Boast on behalf of the planet Earth, a way of declaring to all those Sufficiently Advanced Aliens and would-be invaders "come and have a go if you think you're hard enough!" The Chitauri themselves acknowledge this at the end. Their master Thanos, however, takes it as a challenge.
Badass Crew: Of course! The idea behind the Avenger's Initative was to invoke this trope!
Badass Army: The Chitauri thought they were one of these. And maybe they were. But alas, "We have a Hulk." (And a living legend who lives up to the legend, a demigod, a couple of master assassins. And...a billionaire genius playboy philanthropist.)
Badass Normal: Nick Fury, Agent Coulson and Maria Hill contribute to the fight using S.H.I.E.L.D. weapons, tactics and leadership. Hawkeye and Black Widow fight side-by-side with the superpowered superheroes, on two occasions needing superpowered assistance to get to certain locations.
Bash Brothers: Several team ups, the most notable pairings being Iron Man and Captain America, Thor and the Hulk, and Black Widow and Hawkeye. Though Cap and Widow have their moments too.
Batman Can Breathe in Space: The Chitauri don't seem to have any apparatus other than their (possibly ornamental) metal masks while riding their sleds in outer space. Of course, they may come from a dimension where the laws of physics are a bit different or their strange cyborg bodies may not need air.
Batman Gambit: Loki's plans. All of them rely on pressing the hero's buttons to provoke reactions that he thinks will help him.
Beam Spam: Late in the final battle a group of Chitauri aircraft manage to corner the Hulk and start blasting the bejeezus out of him, though it apparently doesn't do any lasting damage.
Beauty Is Never Tarnished: Maria Hill gets small cuts on her cheek and forehead, though it notably stays there for the rest of the movie. Black Widow takes an accidental backhand from the Hulk and it doesn't even smudge her makeup, let alone pulverize her ribcage.
Bench Breaker: Black Widow does a flip while tied to a chair, shattering it on impact and freeing herself.
Berserk Button: Don't tell Thor to put his hammer down. As Cap found out, he'll put it down...on your head.
Pretty much any insult will push Thor to a towering rage, at least before he learns humility in his banishment to Earth. Although he does still go nuts against Tony Stark (after the latter has turned and started to walk away) for calling him a "tourist."
BFG: Coulson retrieves one based on the Destroyer's remains from the Helicarrier armory to face Loki.
Agent Phil Coulson also counts: barring Captain Rogers, Coulson is probably the kindest and most polite character in the cast, and yet he's one of the top agents of S.H.I.E.L.D and one of Nick Fury's trustees, a position you do not get if you're not able to kick some serious ass. The way he gives Loki a "The Reason You Suck" Speech and shot him while bleeding to death speaks for itself. Also, Coulson's method of getting through the Russian mafia's call screening:
Coulson: You're at 114 Solenski Plaza, third floor. We have an F-22 exactly eight miles out. Put the woman on the phone or I will blow up the block before you can make the lobby.
Big Applesauce: The climactic fight sequence occurs in Manhattan. For once this is fully justified; it is explicitly stated that Loki is trying to show off and make a spectacle of his Evil Plan, so it makes sense that he'd deliberately choose New York. Captain America tells the Avengers to try to contain the Chitauri in Midtown around Stark Tower (in Real Life the site of the Met Life Building), and within three blocks of the Park Avenue Viaduct in front of Grand Central Terminal.
Big Bad: Played with. Loki is the main threat and the one who needs to be stopped but it's clear from the start that he's a mere errand boy for a bigger threat.
An elderly German man defiantly stands against Loki in Stuttgart. As Loki is about to kill him, Cap bursts in, blocks the blast with his shield, and fights.
Then, when Loki has Cap on the ropes, Iron Man arrives to provide backup.
Later, Thor saves Black Widow from Hulk on the Helicarrier.
And when the Avengers Assemble to stop the invasion from destroying New York.
And Hulk leaping to catch Iron Man as he falls helplessly from the portal.
When one of the leviathans is closing in on an office building and the people inside can only watch with horror, here comes the Hulk, storming through cubicles to the rescue.
Played for laughs when Bruce does this... by slowly chugging into Manhattan and up to the badly-outmatched heroes on an ancient, ridiculous-looking, tiny little motorcycle with the oh-so-inspiring comment "Well, this all looks... horrible."
Bigger Stick: S.H.I.E.L.D.'s true plans for the cube. The consequence of the dawning age of superheroes.
Big Good: Nick Fury, considering he (nominally) commands all of the heroes and everyone who outranks him is a Knight Templar jerk. In actual battle, it's good ol' Cap, who's the most natural leader.
Big Guy Rodeo: At one point, Thor hops on Hulk's back and starts choking him with his hammer.
Big "NO!": Thor does one when Loki stabs Coulson in the back.
Blatant Lies: When Tony Stark, still trying to get Coulson to leave him alone, tells him that official consulting hours are between eight and five every other Thursday. You can even hear a tiny pause before "Thursday" where he's thinking of a day of the week they're not on. Coulson doesn't care.
Blood-Stained Letter: After Coulson is killed, Nick Fury presents his beloved collection of Captain America collector's cards to the team, still wet with his blood. After the team has gone to face Loki, Agent Hill says the cards were in his locker, at which point Fury admits he needed something to motivate them.
Bloodless Carnage: This kind of goes without saying by now but it was particularly noticeable in this film. The army attacks Manhattan without a single person being visibly injured. Despite this, the Avengers seemed quite concerned about the safety of the people on the streets. Afterwards, there's a video of a wall commemorating those who died in the battle, so clearly there were quite a few off-screen casualties. In the UK 3D release, however, alien gore does splatter out onto the audience in the final battle.
Blue Eyes Take Warning: When Loki mind-controls someone, their eyes glow bright blue as an indication (the same color as the gem in Loki's staff and the color of the Tesseract, clues that both use a similar power source).
Blunt Yes: Loki responds this way when Thor asks him if he considers himself above the humans.
The S.H.I.E.L.D. agents all use conventional firearms. Even Nick Fury's RPG launcher fits here.
During one of his Insufferable Genius monologues, Tony wonders aloud how Fury can see the monitors stationed to his left when he's missing an eye. He's told that Fury just turns to look at them, which Tony comments on as inefficient.
When Fury wants to move the crippled Helicarrier south, the helmsman remarks that navigation systems are offline. Fury's response:
Nick Fury: Is the sun coming up? Helmsman: ...Yes, sir. Nick Fury: Then put it on the left!
When Tony uploads a computer virus to unlock all of S.H.I.E.L.D.'s files to find out what they're really doing with the Cube, Cap decides it's taking too long. So he just breaks into the armory, steals a captured HYDRA gun, and dumps it on the table in front of the team.
Boring Invincible Hero: Averted. Maria Hill is injured by a grenade and Fury is shot in the chest. He's wearing a bulletproof vest, but he's still winded. During the final battle, each of the Avengers is winded, wounded, or pinned down. Coulson also dies.
Bottomless Magazines: Captain America and the Elite Mook he fights at the Helicarrier never seem to run out of ammo in their rifles. Hawkeye runs out of arrows. Also, Black Widow is seen reloading one of her guns, and scavenges alien weaponry.
Breaking the Fellowship: Part of Loki's Evil Plan early in the film, by causing Bruce Banner to turn into the Hulk and help break the Avengers group apart so they'd be out of his way while he summoned the Chitauri to Earth. It nearly worked.
Break the Cutie: Black Widow to a certain degree. She is chased by the Hulk in the Helicarrier and is nearly smashed by him, causing her considerable distress. She also confesses to Hawkeye that she's been "compromised" by Loki's Hannibal Lecture in spite of playing a Wounded Gazelle Gambit to trick him.
Break Them by Talking: Loki loves doing this — with obvious relish — every chance he gets. Which is presumably why he's muzzled at the end.
Brick Joke: Used repeatedly, mercilessly, and at every opportunity.
Steve Rogers tells Nick Fury that he isn't out exploring the wonders of the 21st century because "I doubt anything could surprise me any more." Fury replies "Ten bucks says you're wrong." This just appears to be a figure of speech, until SHIELD's aircraft carrier takes off into the sky and turns invisible. Rogers appears on the bridge, and wordlessly passes Fury $10.
Agent Coulson's Captain America trading cards are mentioned to Steve and that he'll probably childishly ask him to sign them. The second time the two are together Coulson sheepishly asks if he will sign them. After Coulson's death, the cards appear again in a much darker context.
Tony says they should all eat at a shawarma joint he saw. In the second stinger added to the U.S. version, they do. Everyone except Tony and Bruce are in full costume, and the place is still messed up from the attack. There's almost no way anyone would notice it on the first viewing, but Tony bounces past a shawarma joint when he crash-lands after his "Jonah maneuver" through one of the Leviathans. It's a blink-and-you-miss-it sort of thing, and is kind of amusing if you consider what it says about Tony.
Tony calls an employee of S.H.I.E.L.D. out on playing Galaga instead of working. It sounds like he's just holding the floor as a distraction, so he can plant his virus bug to break into S.H.I.E.L.D's mainframe. Cue the end of the scene where we see a S.H.I.E.L.D grunt sheepishly switches windows and goes back to playing Galaga.
After Banner riles off some Techno Babble (It's real science disguised as such), Tony says, "Finally! Someone who speaks English," to which Steve wonders bemusedly, "Was that what that was?" Later, Tony attempts to explain to Steve what to do while they make some repairs, but does it in such a way that Steve has to tell him "Speak English!"
Hawkeye commenting that he'd like to put an arrow in Loki's eye. It comes back twice: Once in Manhattan, he fires an arrow at Loki's eye, Loki catches it, and it explodes. The second return is at the end of the battle, when Loki crawls out of his Hulk Smash hole. The Avengers are all circled around him, and Hawkeye is front-and-center, with an arrow pointed at Loki's face (presumably aimed for the eye).
A rather heartwarming one occurs when Pepper asks Phil Coulson about his girlfriend, only to be informed that they broke up when she moved back to Portland. Later, when Tony arrives on the Helicarrier, he's shown offering to fly him out to see her on his private jet.
Before Loki brainwashes Barton his comment is "You have heart." Later in the movie when he tries to brainwash Tony Stark his attempt is blocked by the arc reactor. Ironic when you consider that all the way back in Film/ Iron Man 1 Pepper's birthday gift to Tony is his original arc reactor, as "Proof that Tony Stark has a heart."
Several characters, most notably Natasha and Tony, express curiosity about Banner's "secret" for how he's managed to avoid getting angry and keep the Hulk from emerging for so long — Natasha speculates about yoga, while Tony's guesses include "Mellow jazz? Bongo drums? Big bag of weed?" Just before joining in the final battle, Bruce reveals it: "That's my secret. I'm always angry."
During their first scene, Tony tells Pepper to take "some of the credit" for Stark Tower, eventually settling on 12%. Her reaction prompts him to respond "I'm gonna pay for that later, aren't I?" When Coulson shows up with some S.H.I.E.L.D. intel for Tony to look at, Tony tries to get Pepper to send him away, saying "I thought we were having a moment." She responds "I was having 12% of a moment."
Broad Strokes: The approach taken with Bruce Banner/Hulk. Iron Man, Thor, and Captain America have multiple characters and/or plot elements from their films play into this film, Banner/Hulk is the only one to show up from his film, and outside of brief glimpses of footage and a joke reference, his film is never really alluded to at all. In addition to being re-cast, the characterization of Banner and Hulk are quite different from in 'The Incredible Hulk'. That film is the only Pre-Avengers film you could miss completely, as Banner/Hulk are effectively re-introduced in this film.
Building of Adventure: Stark Tower is a somewhat mundane example that's just focused around awesome Iron Man stuff but a Freeze-Frame Bonus at the end reveals that he plans to give the building a substantial upgrade that includes a hangar for a Quinjet as well as giving the various members personalized floors of their own.
Bulletproof Vest: After getting shot, Fury makes it a point to extract the bullet from the vest and show it to the camera as per trope tradition. Cap also gets shot during the battle, but survives thanks to his armor.
Yes, Loki, you are a god, but that doesn't mean you should try to push the Hulk around.
Similarly, Tony shocking Bruce Banner mid-conversation with a miniature cattle-prod to see if he can control his episodes. It's an aversion as Tony is playfully teasing, rather than bullying. In fact, Steve seems more annoyed about it than Bruce himself.
Tony invokes this towards Loki, casually pointing out that he's met some of the most dangerous people on the planet and pissed off "every single one of them". What makes Loki think this will end well for him?
Butt Monkey: Despite being the Big Bad, Loki seems to have a few spells of being one of these, especially towards the end of the film. Almost every Avenger gets his goat oncenote To wit: Cap managed to interrupt his gloating in Stutggart with a deflected beam attack; Natasha out-tricks him into revealing his plan to unleash the Hulk; Stark No Sells his Mind Control scepter thanks to his Arc Reactor; Clint manages to hit him with an exploding arrow, which Loki thought was harmless when he caught it mid-air; and of course Hulk cuts him off from his Villainous Breakdown with some good ol' Metronomic Man Mashing.. Even Phil Coulson gets in a good shot.
Poor Thor. He gets beat up by Iron Man, Cap (sort of), and the Hulk.
Tony Stark. A great deal of the humor in the various action sequences involve him first being genuinely badass, but then casually getting the shit kicked out of him (once by an inanimate propeller) because he a) is incredibly smart-alecky and boastful, and getting smacked around stops him from coming off as annoying, and b) wears a suit of Powered Armor, so getting the shit kicked out of him doesn't actually hurt anything but his pride all that much.
Cain and Abel: Loki and Thor themselves as usual. Loki tries to outright murder his brother Thor when he was safely imprisoned (although it's very questionable whether he thought the trap would kill Thor). Thor later makes one last bid to talk Loki down during the climactic battle. Loki's response is to pull out a knife and stab him.
Call Back: Stark scoffs at Fury's plans to use the Tesseract as a "nuclear deterrent". This mirrors Stark calling himself America's nuclear deterrent in Iron Man 2, before finding out he actually wasn't the only one who could duplicate Arc Reactor technology.
Natalie Portman would have made a cameo, but she was pregnant during filming, reducing her cameo to an image on a video screen as Coulson and Thor have a conversation about her. (in Thor: The Dark World Jane Foster is a little peeved that Thor didn't look her up when he was in town.)
At the end, mid-credits, Thanos.
Stan Lee, naturally, as he's done it in almost every other Marvel movie thus far. This time, as a man playing chess in the park being interviewed by a news crew. "Superheroes? In New York? Gimme a break!" A deleted scene on the Blu-ray shows a different Stan Lee cameo which takes place near the beginning of the movie where he gives Steve some girl advice.
Camera Abuse: The camera lens gets splattered with gore multiple times.
The Cape: Captain America, who's definitely the most upstanding guy around. He's worried a bit that some may view this as old-fashioned in the cynical 21st century, but Coulson tells him that right now we may need his brand of "old-fashioned."
The Captain: Captain America (duh) but the man proves his rank isn't just for show when he displays terrific organization and leadership abilities. During the final battle he manages to get everyone together and quickly tells them all how to play to their strengths for maximum group benefit. (Hawkeye being the team spotter, himself and Black Widow evacuating people on the ground, Stark and Thor taking out enemies in the air, and Hulk... smashing stuff.)
Captain Obvious: When asked to inspect an electrical panel full of wires, fiber optic cables, circuit boards, and assorted other electronic gizmos, all Captain America can report is a distinctly sarcastic, "It seems to run on some form of electricity."
Tony Stark: Well...you're not wrong.
Car Cushion: Cap gets this treatment. It helps that he only fell about one story on to his shield and is empowered by the Super Soldier Serum. He still takes at least a couple of minutes to get going again; it really hurt.
Car Fu: Thor takes out a few mooks with a car using a swing of his hammer.
Catch a Falling Star: Towards the end of the movie, Iron Man is falling from low earth orbit, unconscious and with no power in his suit. The Hulk leaps by, catches him, drags down a nearby building with his hand to slow both of them to an Iron Man-safe velocity, then cushions Tony with his own body for the final 20 feet or so to the pavement.
Catchphrase: Averted: nobody says "Avengers assemble!" Depending on which scene they tried to work it into, it was deemed too cheesy or redundant of a line. However, there is the UK title, and cast members reportedly texted one another the phrase before gathering socially in their off-hours.
Chairman of the Brawl: Black Widow beats up criminals with a chair and she doesn't even have to get up from it.
Changed My Mind, Kid: Bruce Banner reluctantly lets himself get recruited for his scientific skills, and makes it clear that he's only there to help find the Tesseract and won't be sticking around once the fighting starts. After he leaves, Tony Stark is confident he'll decide to come back and help, but everybody else assumes he's gone for good. Tony turns out to be right.
Tom Hiddleston described Loki in this film as having "seen things" while falling through the void, saying that getting tossed through a wormhole of his own making has really affected his psyche and his development as a villain.
Tony Stark starts out the snarky anti-hero of previous films, but when Cap calls him out on the selfish, lone wolf approach he's taken to superheroism, Tony realizes what it really means to be part of a team and to put his life on the line for someone else. It helps that Agent Coulson, someone that Tony knew personally, does exactly this and suffocates when his suit shuts down as a result.
Bruce Banner must continue his arc from the previous film, accepting that the Hulk is a part of him, for good or ill.
Captain America goes from being confused about his place in the present and wondering if Good Is Old-Fashioned in the present, to using his inherent goodness and tactical skills to lead the Avengers and ends up inspiring people, as shown in the news reports after the invasion.
Thor goes from continually trying to reach out to and believe in his brother, Loki, and not being a good team player, to becoming a much better teammate and eventually realizing he has to stop Loki.
Loki's personality devolves from his unusual antagonist status of an Anti-Villain with Byronic Hero traits whose actions, while not enjoyed by Thor, were at least reasonable and well-followed, (his methods were the issue) into the traditional villain antagonist.
Chekhov's Gag: Black Widow quips it's only a matter of time before Coulson begs Steve Rogers to sign his trading cards. This quickly turns out to be the case. When we see the cards in question, they're still wet with Coulson's (fake) blood.
Much is made early on of the newly-launched Stark Tower, which runs on its own arc reactor, and how it could be interpreted as a giant monument to Tony's ego. Later, Steve and Tony figure out that Loki needs access to a big power source to activate the Tesseract, and that Loki wants the invasion to be a monument to his own ego.
Cap berates Tony for his inability to be heroic, especially when it comes to making sacrifices. Naturally, Tony makes a Heroic Sacrifice at the end. He suffocates, but survives.
Early in the Final Battle, Black Widow kills a Chitauri mook by ripping a bunch of electronics out of its neck, establishing these aliens as at least party cybernetic. At the climax, Iron Man throws a nuke at the Chitauri command ship, shutting down the attack force.
Nick Fury's description of Loki's jail cell is a classic example: as soon as he mentions it's designed to be dropped out of the Helicarrier and will fall 30,000 feet, you know that capability is getting put to use somehow.
Cap says that Loki's staff looks like HYDRA technology, which was powered by the Tesseract. S.H.I.E.L.D. too was designing HYDRA-inspired weapons powered by the Tesseract. And at the end, Loki's scepter is the only thing that can pierce the Tesseract's energy barrier.
In the flashback scene where The Other is threatening Loki, one of the Leviathans "swims" by in the background.
Averted with Thor's lightning providing Stark's armor with a 475% overcharge, as demonstrated accidentally during their forest skirmish. Although a potentially useful if self-destructive tactic (the armor didn't come out of it unscathed), this is never used during the final battle against the Chitauri.
Averted with the shockwave produced by Thor's hammer interacting with the Captain's shield. Despite being a classic setup for the maneuver's reuse during the final battle, it does not appear again. Perhaps if the final battle hadn't been in an unevacuated city...
Early on Tony is introduced while totally underwater, revealing that his suits are totally airtight and temporarily life-sustaining without an outside source of oxygen. This comes in handy when he needs to survive in the vacuum of space for a while during the climax.
The Chessmaster: Played with. Nick Fury is doing his best to be one, but unfortunately he is trying to manipulate two of the smartest people on Earth, a proud and reckless demigod and a Knight in Shining Armor. The first two don't buy his bullshit, they spill the beans to the other two, who don't take it nicely. Fury has to give up, apologize and play, oh, just a bit straighter... but he's still The Spymaster and a Manipulative Bastard.
Chewing the Scenery: Loki gets his moments in the cell tearing into Black Widow and trying to do the same to Hulk.
Cold Sniper: Hawkeye, with his bow. The trope is particularly in effect during the first half of the film while he's under Loki's Mind-Control Device.
Colony Drop: Part of Loki's plan involves having the Hulk wreck up the S.H.I.E.L.D. Helicarrier, thus distracting everyone from the brainwashed Agents sabotaging the engines until it drops like a stone out of the sky.
Colour-Coded for Your Convenience: Every single S.H.I.E.L.D. Quinjet we see throughout the film is painted grey on top (a camouflage shade called Dark Ghost Grey, very appropriate for a non-existent paramilitary organization), except for the one that delivers Barton and his mercenaries to the helicarrier. Barton, or Loki, or somebody, took the time to have this particular Quinjet painted... BLACK. That should have tipped off the Hovercarrier air traffic controller, even if the whole "unscheduled arms and munitions" business didn't....
During the assault, over the loudspeaker is the announcement that the intruders are wearing S.H.I.E.L.D. gear, making them harder to take out.
The Hulk has a style that consists of bashing, smashing, and using whatever is nearby. It is most obvious in his fight with Thor, who is a seasoned warrior with a much more refined style.
Black Widow, a highly-trained martial artist, is not above resorting to groin kicks and biting.
Hawkeye is a talented archer, but the first weapon he uses in the film is his handgun. In his second combat sequence, he also carries a handgun and a knife as backup for his bow. He also resorts to hair-pulling in his fight with Natasha.
When Hawkeye and Black Widow fight each other, there's a noticeable amount of biting, scratching, and hair-pulling among the fancy martial arts moves.
As in his own film, Cap relies on his shield because of its powerful symbolic value but he'll still use a gun or any other weapon that's handy if the need arises, cuz ya know, there's a war on out there.
Banner goes out of his way to avoid saying "Hulk", instead referring to his alter-ego as "the other guy" — justified in his case by his deep-seated shame and guilt about "the other guy's" very existence. Other characters use the name, however, and he does manage to slip at least once.
Natasha directly calls Clint "Hawkeye" when she's riding a Chitauri hovercraft on piggyback because it's his radio callsign. Dr. Selvig also refers to him as "the Hawk" in the first scene. Otherwise, people refer to him as Clint or Barton.
Whilst being interrogated, Natasha Romanoff is referred to as "the famous Black Widow", but this is the only time her codename is used. Nick Fury typically refers to her as "Agent Romanoff". Clint refers to her as Natasha or Nat.
Tony is once again never referred to as "Iron Man" during the film, with closest being Thor calling him "Metal Man" and a reporter making the clear distinction of "Tony Stark's Iron Man" during one of the reports on the battle in Manhattan.
A mention is made of Captain America trading cards and Banner mutters the name once. A civilian bystander also refers to him as Captain America in an interview on the news during the epilogue. He's usually called just "Steve", "Rogers". He is also called "Cap" and "Captain" too, which may be a subversion, or may be in reference to his army rank. It's not clear.
This even applies to the MacGuffin, which is called either the Tesseract or "the Cube", but never the Cosmic Cube.
Conflict Ball: Loki gleefully gets captured just so he can toss one into the S.H.I.E.L.D. Helicarrier amongst the would-be Avengers. The crux of this is to draw out the Hulk from Banner. The ball also seems to be a literal object, as Loki's staff is implied to be causing the dissonance between the members.
Consequence Combo: Loki is playing for rulership of Earth... but it's made very clear by the Chitauri that failure is not an option, and things will go very, very badly for him if they don't get what they want. When Thor tries to talk him into abandoning his scheme, he takes one look at the portal, looks genuinely terrified, and claims that it's too late to back out now even if he wanted to.
Black Widow mentions to Coulson that Stark doesn't trust her after finding out she's a S.H.I.E.L.D. agent in Iron Man 2.
We get clips from previous films either as Flash Back or as raw footage, especially when it comes to Captain America.
Pepper Potts' previous meetings with Coulson are referenced.
When inspecting the hologram of the Tesseract at Stark Tower, Tony gets a look on his face that says: "Wait a minute, I know this! This cube was in my father's journal..."
Banner mentions nearly destroying Harlem, referencing the Hulk's fight against the Abomination at the end of The Incredible Hulk.
Banner also mentions that at one point he tried to kill himself, but the "other guy" spat out the bullet. This was shown in the alternative opening to The Incredible Hulk.
Iron Man refers to the new suit as Mark VII, indicating past armors. He also uses the lasers from Iron Man 2, and they're still apparently one-offs until he upgrades to the Mark VII suit, which has them on auto-reloading clips.
Practically every plot element of Thor was mentioned throughout the movie.
Tony still doesn't like to be handed things.
Tony mentions that his father knew Captain America. Who found the Tesseract while searching for the Captain?
Insulting Thor to his back is still not a good idea.
Black Widow makes an allusion to Tony's talk with General Ross in The Incredible Hulk.
Jane Foster is explained as being transferred to a distant place to protect her from Loki. Her actress was very pregnant at the time of production.
The gun Coulson uses on Loki was reverse-engineered from the Destroyer in Thor.
The Hulk can't lift Mjölnir because he isn't worthy.
Captain America, when first meeting Loki in Germany, notes that the last time he went to that location, he also had to deal with someone who believed he was higher than everyone else, referring to either Red Skull or Hitler.
Cap says that Loki's scepter may run on magic, but it looks like HYDRA technology. Thor stated the reason in his own movie: Asgardian technology is so far advanced beyond current human tech that it is indistinguishable from magic to us.
Cap destroyed a punching bag when Fury walked in at the end of his movie. When Fury walks in on him in this movie, he's working a punching bag and knocks it off its chain, though he doesn't destroy it. When he's walking out, he picks up a punching bag from a row of them he has on the floor.
Tony's line about bringing "the party to you" is a callback to a line Natasha says to Tony in Iron Man 2 when the Hammer drones attack.
Loki flat out lampshades it when he traps Thor with an illusion trick.
Loki: Are you ever not going to fall for that?
The conversation Thor and Loki have just before trading blows in the climax mirrors the one Odin and Laufey had after Thor's destruction of Jotunheim.
A very subtle one, but a lot of Tony's dialogue while mourning over Phil Coulson reflects Yinsen's death in the first Iron Man movie.
The beam of light generated by Selvig's portal device resembles the beam created by both the Bifrost in Thor and the overloading Arc Reactor in Iron Man. The generator itself incorporated design elements from both the Bifrost (where the beam emerges) and the Arc Reactor (the coil surrounding the iridium).
Colonel Fury makes a note of how wars are won by soldiers, not weapons, to the council. Colonel Philips makes a similar statement (Quoting Patton) in Captain America.
When Tony is encouraging Bruce to view The Hulk not as a curse, but as a gift, he references the initial chest injury he suffered in the first Iron Man movie. He also mentions the levels of gamma radiation Banner was exposed to should well have killed him, but he survived for a reason. This is also a Call Back to how Tony viewed his own survival of the attack in Afghanistan.
Tony out-Batman's Batman for designing a suit that can deploy and attach itself to him while he's falling out a building.
Hawkeye has exploding arrowheads, hacking arrowheads, super-heating arrowheads, shrapnel arrowheads, grappling hook arrowheads, exploding arrowheads disguising to look like normal arrowheads so on the off chance the target has the Super Reflexes to catch the arrow they won't recognize it as an exploding arrowhead...
Crucified Hero Shot: Tony gets one at the climax. After sacrificing himself to fly the nuke into space, he loses consciousness in the vacuum and and slowly falls backwards, arms outstretched and head hanging limp. And for a double-whammy of symbolism, he hauls the nuke up through the portal while carrying it on his back. He also sacrifices himself not while defeating the enemy, but while saving the WSC (who qualifies as a council of state officials) from the sin of murdering millions of civilians, skims over water to catch the nuke, carries it on his back and over one shoulder through the city while watched by thousands of bystanders and news-viewers, ascends into the heavens, suffocates and dies (temporarily) high above the city and all alone, and then returns to earth, where his limp body is caught and lowered to the ground and surrounded by his teammates before he then comes back to life and greets them. And the way the repulsor ports in his palms look while he's falling is pretty noticeable as well. The only thing missing from the allegory was a bit of Pietà Plagiarism.
At the climax, Loki loses his cool and yells at the Hulk. This is exactly as bad of an idea as it sounds.
You know the gigantic biomechanical Leviathan the trailer builds up as a grave threat? After roughly five minutes of being unstoppable, the Hulk stops the first one with a single punch to the face, setting it up to be blasted by Iron Man.
Cursed with Awesome: This is how Tony Stark has come to view the electromagnet and the miniature arc reactor plugged into his chest 24/7 and are the only things keeping him alive. He spends a good deal of the film trying to convince Bruce Banner that the Hulk is a similarly awesome curse. For Tony, the "awesome" part kicks in when Loki tries to brainwash him, but he can't, because his heart is protected by the arc reactor.
When Hawkeye fires an arrow at Loki while he's riding a Chitauri glider, Loki catches it in mid-air with his Super Reflexes and looks at it, as if to check what type of arrow it is. The arrow in question looks markedly different from the explosive one Hawkeye used earlier to blow up part of the Helicarrier, so Loki smirks when he's sure he's safe. This turns out to be a setup and the arrowhead opens and explodes anyway.
When Barton is mind-controlled, he realizes Fury is stalling so the place will collapse and they and the Tesseract will all be buried, keeping it out of Loki's hands, and informs Loki.
Loki's also pretty on-the-ball about getting up to speed on all of the Avengers' dossiers. His capture by S.H.I.E.L.D. was merely so he could set off Bruce Banner, who he knew was stationed on the Helicarrier, while all the other Avengers members were present and eliminate them together when the Hulk loses control.
Deadpan Snarker: All of the Avengers (sans Thor and for the most part, Cap) as well as Loki have their moments.
Thor: Listen well, brother — (Gets bowled over by Iron Man.) Loki: (amused) I'm listening.
A Death in the Limelight: In as much as it's possible in an ensemble cast. Coulson gets a lot more character development here and in the tie-in comics, including that he has/had a romantic relationship with someone who may have been a cellist, and that he's a giant Captain America fanboy.
Death Is Dramatic: Despite numerous casualties suffered by both attackers and S.H.I.E.L.D. agents on the Helicarrier the only one that any time is spent dwelling on is Coulson. Barton does ask how many died because of him but he seems more angry that he was responsible rather than mourning their deaths.
The old German man who refuses to kneel before Loki.
Agent Coulson, who shows no fear when confronting Loki.
Demoted to Extra: A number of important supporting characters from the previous films receive much less screentime in this film.
Gwyneth Paltrow reprises her role from Iron Man, but in a minor capacity. Robert Downey Jr. asked for her to be included as a way of exploring the Potts/Stark relationship that was established at the end of Iron Man 2. Whedon agreed, because "you should always, given the opportunity, put a Gwyneth on-screen."
Dr. Selvig also returns from Thor, in a role that's more plot-important but doesn't necessarily get any more screentime.
Cap especially seems this way, especially after the point where he gets flung out of a building by a bomb, is clearly worn down, and yet he gets up and keeps fighting.
Black Widow, especially where Hawkeye is concerned. On the Helicarrier, she takes a full on hit from the Hulk and is obviously rattled and injured, to the point of a mini-BSOD. When she hears Hawkeye is in the complex? She gets right up and takes the fight to him.
Hulk, naturally. It's in his character, after all: he'll just keep fighting. Nothing you throw at him will stop him.
Thor when it comes to Loki and Earth. It's implied that he had his father use a lot of dark energy to send him back to Earth, and when he gets there he seeks out Loki with almost single-minded drive.
Coulson takes a spear through the back and still manages to give Loki a "The Reason You Suck" Speech and blast him through a wall as he's bleeding out.
Tony probably takes more punishment and damage than everyone else combined (the Mark VI armor is one good tap away from falling to pieces by the end of the second act) and still keeps going, making hasty repairs on the fly and pushing his servos to the limit when trying to restart the Helicarrier's engines.
Maria Hill in the pre-credits sequence, when she furiously chases down Loki, Clint, and Selvig in a Jeep through the rapidly-collapsing base, shaking off multiple crashes, gunfire, and falling debris. It takes an entire tunnel caving in on top of her and crushing her engine flat to finally stymie her.
The NYPD officers in the final battle. There's a wormhole to the other side of the galaxy gaping open above Manhattan, aliens with futuristic weapons and giant mechanical whales are pouring in and swarming the city, and yet New York's Finest are still out in the streets, keeping order, directing the evacuation, and trying to form a defense.
Deus ex Machina: On the DVD Commentary, Joss Whedon calls the Incredible Hulk a "Deus Ex Hulkina", showing up out of nowhere to help out the others at least twice in the movie. He justifies it by pointing out that if they showed every second of what the Hulk was doing, the movie would have gone far over budget.
Deus Ex Nukina: As the Avengers were not defeating the invasion, the Council decided to Nuke 'em. But, once the nuclear missile was in the air, the Deus Ex Nukina comes into play: Iron Manages to grab it in flight, change its path, take it through the portal, and let fly straight to the alien mothership. And, when it was destroyed, all the invading army died immediately. Happy ending, time for some Shawarma!
Disproportionate Retribution: Loki's plot to take control of Earth is largely driven by jealousy and resentment towards his adoptivebrother Thor, as well as rage at being deceived about his true ancestry. He wants to subjugate the entire population of Earth—a planet which Thor treasures and protects—thereby wiping out many of the people that Thor cares about. In addition, Loki feels that he was cheated out of his rightful place as the ruler of Asgard.
Thor: So you take the world I love as recompense for your imagined slights?
Divide and Conquer: This is Loki's plan for dealing with the Avengers; he targets Bruce in particular. He succeeds for a while even after they realize what he's up to.
Divided We Fall: Happens quite brutally, with tragic consequences, during Act II.
Massive damage to New York ensues after a surprise attack. The ending with post-strike reports just screams 9/11. Also, you will find few Americans who remember that day vividly and who empathized with the office workers who weren't reminded of it in the scene when the office workers look out the window to see, not a plane, but an equally impossible to imagine giant bug creature. (None who didn't feel a slight sense of satisfaction in seeing the Hulk racing through the cubicles to the rescue.)
At one point, a Leviathan exits from a building and you can see the building begin to fall behind it in a fashion similar to the World Trade Center towers.
A more comedic moment: when Loki fails to brainwash Tony with his staff, he looks taken aback and says this has never happened to him before. Tony makes an idle comment about performance issues.
When Iron Man lets go of the nuke, it does a fair job of being the Space Shuttle separating from its external fuel tank. Though it's the shoulder jets from the Iron Man armor falling off, the imagery is there.
Downer Beginning: The film opens with Loki killing over a dozen people, brainwashing one of S.H.I.E.L.D.'s top agents along with a renowned scientist, and escaping with the Tesseract as an entire S.H.I.E.L.D. base is destroyed and Nick Fury escapes by the skin of his teeth. Cue title card.
Drama-Preserving Handicap: Inverted for Iron Man. Whereas in his own movies he's been forced to go into the final showdown with some kind of handicap (the older, inefficient Arc Reactor in the first movie, having already used his biggest gun in the second), Tony Stark puts on a brand-spanking new, and much improved, armor just for the big climactic battle after putting his previous suit through the wringer.
The Dreaded: Even his own team members are afraid of the Hulk.
Dream Team: The best the Marvel Cinematic Universe has to offer.
Banner reveals that he once tried to commit suicide, but the Hulk took control and spat the bullet out, which happened in a comic AU miniseries, and was a deleted scene from The Incredible Hulk.
Subverted with Selvig. After he wakes up from Loki's brainwashing, Natasha finds him looking over the edge of Stark Tower's roof, like he's thinking about jumping. Natasha tries to talk him down, only for him to reveal that he's not looking at the ground; he's looking at Loki's scepter a few stories down, which is the key to closing the portal.
Dropping the Bombshell: Banner reveals he knew all along that S.H.I.E.L.D. had a contingency plan to kill him in case the Hulk got out of control — and then he drops the real bombshell, which is that the plan won't work because he's already tried to kill himself.
Dying Moment of Awesome: Agent Phil Coulson gets stabbed. Despite this, he gives Loki a "The Reason You Suck" Speech and blasts him through a wall with a BFG. He tells Fury he's okay with going out this way, because it will give the Avengers — specifically Tony and Cap — the push they need to work together as a team.
Dynamic Entry: When Stark flies in to aid Cap, he swoops in and blasts Loki before he's close enough for Loki to see Stark clearly.
Dysfunctional Family: Thor and Loki have a rather rocky reunion. Hemsworth has noted that Thor's attitude in this movie is a mix between anger, disappointment, and protectiveness towards his little brother.
The ex-Lonely Rich Kid orphan whose replacement-father figure tried to murder him and steal his company and became a supervillain?
The Shell-Shocked Veteran who was preserved in ice since 1945 and woke up to find that the war he was made to fight was over and everyone he knew was dead?
The guy being chased around the world by his ex-girlfriend's father who is literally out for his blood due to his, uh, personality disorder?
Banner deserves a special mention because he probably has PTSD (depending on how much of The Incredible Hulk is still canon thanks to its Early-Installment Weirdness), and almost definitely has dissociative identity disorder, which is generally believed to develop as a defense mechanism against childhood trauma.
The Russian assassin who was stolen from her parents and trained from childhood to be a cold-blooded killer?
The former orphan of an archer whose emotions get destroyed so thoroughly and will definitely blame himself worse than Spider-Man if the invasion succeeds?
Or to top all of them put together, the crown prince of a godlike alien dimension whose little brother is a throne-grabbing, world-conquering, Daddy Issues-plagued, fratricidal, patricidal, genocidal maniac from a completely different species than him and has a case of Sibling Rivalry so intense a squabble over daddy's approval between the two of them leveled a town?
The correct answer is, of course, all of the above! Furthermore, all the egos visible from space having to exist together in a single room. These issues have a very strong effect on the characters' volatile, overly-developed, wildly divergent, intra- and inter-personal conflict-ridden Type-A personalities and actions, too. In the words of WSC, they are "isolated and unstable". In the words of Loki, they are "lost creatures". In the words of Bruce Banner
Banner: What are we, a team? No, no, we're a chemical mixture that makes chaos. We're a time bomb.