Korvac's plotline never went anywhere after his debut, though Peter Quill essentially says "Leave this kind of stuff to us, you really don't want to know what else is out there," to both Tony and the audience.
Kang's final episode never resolved his main arc, but it will have to do as a conclusion to his story.
What happened to his minions?
The romance between Hawkeye and Widow was never even acknowledged after she was revealed as the Reverse Mole.
Madame Viper was major character in Skrull Saga, with the hints of Dark and Troubled Pastnote it is implied that something horrible happened to her in the past, which gave her scars on her face and gave her the reason to hate people like Captain America, and Foe Yay between her and Captain America. Yet none of this is brought up ever again, with Cap and Viper becoming enemies in the episode "Along Came A Spider" with no acknowledgment of their relationship in "Prisoner Of War". Also she becomes the leader of the Serpent Society in "Along Came A Spider" and escapes sewer with them in the sewers, but she is mysteriously absent when the Society was attacked and captured by Hank Pym in episode "Yellowjacket, with no mention of her and is never seen or heard again.
Despite it being heavily foreshadowed, we never see Simon Williams undergo his full redemption arc and become Wonder Man. Especially since we're not sure whether he was Killed Off for Real or not.
Absentee Actor: With a ten-man ensemble cast, this happens often. In a strange case, Thor was missing from the Black Panther's introduction episode; and the closest thing we got to an explanation in the episode itself is that Iron Man didn't know where he was, either. The episode, "Masters of Evil", did offer an retroactive explanation, though—Thor didn't know the ID card's beeping was a sign for the Avengers to assemble (now if only we knew why he didn't take the hint when it started saying "Avengers Assemble!" in Tony's voice).
The absences of season 2 are justified, however, as the roster grew and shrank constantly.
Chris Yost:...in true Marvel fashion, Avengers come and go, so Thor was out of the picture except for a one-off in the first half of Season 2, then Hulk was out for the majority of it until the end...every member of the team doesn't have to be in every episode.
A Kree general, Yon-Ragg, is the Kree version of Megatron - his armor is purple, he has a huge fusion cannon on his right arm, he is incredibly ignorant and racist towards humans, and he's voiced by Fred Tatasciore in the same tone of voice as well.
Action Girl: All the women in the series are action girls, heroes, villains and SHIELD agents (even Jane Foster, within her context; that's why Thor likes her).
Adaptation Distillation: The show takes a little bit from most of the "greatest hits" of the Avengers franchise. The line-up is the one of the First Avengers Team by Stan Lee and Jack Kirby, the "Breakout" story-arc derives from the initial story-arc from New Avengers, Iron Man and The Hulk are based partly on their movie incarnations, as are a number of their villains, etc. Captain Marvel, Captain America's second costume and Nick Fury in the second season are taken from the Ultimate Marvel universe. Many episodes were adaptions of specific comic book storylines, such as The Kang War or the Secret Invasion. In general, all of the characters are a Greatest Hits version of various portrayals of them from the comics—for instance, Hank Pym has been Ant-Man, Giant Man and Yellowjacket. Add to that an overload of cameos and continuity nods, and there is everything an Avengers fan may want; if there was something missing, that's just because there was not enough space.
Adaptation Dye-Job: In the comics Hank Pym has blonde hair. In the animated series however his hair is more dirty blonde to light brown rather than straight up blonde (probably to help him stand out against the very blonde Thor, Hawkeye and Captain America when masks come off).
Airborne Aircraft Carrier: The SHIELD helicarier is present as the SHIELD main base of operations, and it even held a prison (The Big House) at the beginning of the series.
All According to Plan: The forces of the Leader captured Thor and took him to the Leader's base. Thor summoned his hammer, and fought against the Abomination until he retrieved it. He thought that, by retriving his hammer, he had won... but the Leader had calculated that, and was in fact expecting him to do that: the Absorbing Man, hidden as the floor, touch his hammer and absorved its power. Unfortunately for the Leader, he did not have enough information about the hammer to know that this would be the Absorbing Man's downfall.
There was also one on the good guy's side. Nick Fury told Tony Stark the greatest secret of the world: that there were shape-shifting aliens infiltrating Earth, and that one had infiltrated the Avengers. And Tony simply goes and shares what he has heard, and asks who is the alien. Yes, really. Obviously, nothing came out of that, the Avengers broke up, and whoever was the alien is now aware of Fury's actions. Way to go, Nick! No: it was All According to Plan. He confirmed that Iron Man is the real deal, and left the yet unknown alien in a position where he may make a mistake and reveal himself. And the aliens surely know about him anyway.
27, 28, 29, 30, 31, 32, 34, 33, 40, 35, 37, 36, 38. Plus, #41 as a "bonus feature."
Ancient Astronauts: It is suggested by Red Skull that the Asgardian monsters are the source of the ancient Norse myths (but he did not explain how did such monsters appear in ancient times, without Red Skull or Tony Stark to make a machine to cross dimensions)
And I Must Scream: Ultron co-ops Tony's armor, making him fight the Avengers WITH HIM STILL IN THE ARMOR. He gets only a few brief moments where his com systems work to try and warn Thor that something has control of his armor.
Also, the Realm of Silence Loki is exiled to in Thor's episode, but then again Loki is such a Magnificent Bastard that it doesn't really faze him.
Which then carries over to Loki's fate after his big plan fails at the end of Season 1. True to Norse mythology, he is trussed up and left in the care of a giant serpent which constantly DRIPS VENOM INTO HIS EYES. Yikes.
Nasty enough by itself, but remember - Loki's immortal. His eyes won't eventually lose their capacity to feel pain: nor can he escape by thirst, starvation or old age. He's there until Odin forgives him or until the world ends... and Odin isn't a particularly forgiving god.
Amora used Chemistro's gun to turn his armor to gold. He remains conscious for what is implied to be several hours before Tony and Janet find him and call for help.
Arbitrary Skepticism: In the episode "459", Wasp doesn't initially believe in aliens. Norse gods, people made of living sound, guys being frozen in the Arctic for forty years, no problem. But aliens? That's just crazy. Hank holds on to his skepticism even longer, even as the evidence starts to pile up.
Justified by the fact that Wasp was teasing Carol, and in Hank's case he points out the was no organic signature and therefore no life. He even justifies his disbelief in this exchange:
Wonder Man considers himself Iron Man's Arch-Enemy, though it's one-sided. Crimson Dynamo also considers himself Iron Man's Arch-Enemy. So does the Living Laser. Let's just say that a lot of people don't like Tony.
Man-Ape to Black Panther
Black Widow to Hawkeye until she revealed she was working for Nick Fury. Afterwards, they shared a kiss.
What do you want with me? Who are you working for? And why would you combine green and yellow with your skintone?
Art Imitates Art: During the siege of Asgard, Balder jumps to a Frost Giant, runs over his body, attacks him at a weak point and the giant falls, with Balder jumping forward and landing as a hero with the fallen giant behind him. The whole sequence was very similar to one made by Legolas to kill an Oliphant in The Lord of the Rings: The Return of the King
Artistic License - Geography: Look closely at the scenes of Earth from space in the "Gamma World" episodes. Apparently, Las Vegas and the American southwest are located in northeastern Canada.
As Lethal as It Needs to Be: Wasp's stings. Usually annoying Beam Spam, occasionally armor-piercingly powerful. During the five-part pilot, she manages to whip off a blast that cut a railroad car in half (a railroad car that was being thrown through the air right at her). It didn't even seem to be a matter of concentration or energy use, because she went right back to her normal Beam Spam right afterward.
The Baroness: Viper always fit this role, but in this version has a tendency to pull grenade pins with her tongue. Which is appropriate, as the Trope NamerBaroness was based on Viper to begin with. The bit about being a Skrull is new, though.
Bait-and-Switch Credits: Episodes from Season Two begin with an Opening Narration creating the impression that the Avengers consist entirely of the "Big Three"-Iron Man, Captain America, and Thor-and the Incredible Hulk. More often than not, the succeeding episode will actually feature only one, two, or three of those heroes, fighting with help from some Avengers who would probably seem unfamiliar to viewers who neither read the comics nor saw the first season. (Moviegoers could at least recognize Hawkeye.)
Bash Brothers: Captain America and Bucky; The Warriors Three; Luke Cage and Iron Fist; Thor and Beta Ray Bill.
Batman Gambit: It turns out HYDRA's attack on the United Nations in "Iron Man is Born" were all a plot to get the Grim Reaper inside The Vault so he could break out Wolfgang von Strucker, the head of HYDRA.
Wasp tricks members of AIM into leading her and Thor to their base.
Thor: Like a Frost Giant's head on an infant's body.
Don't even dare to hurt Janet, lest you push Hank Pym's berserk button and get curb-stomped. Quite literally, as he is called GIANT Man.
Big Applesauce: The Avengers Mansion, Stark Industries, and several other places important to the team are located in New York City. Some episodes also saw the Avengers either saving or visiting some real-life NYC landmarks. Iron Man somewhat lampshades this in the series finale:
Pulled by Black Panther, saving Captain America from Baron Zemo. Cap returns the favor in "Panther Quest".
Played with in "Masters of Evil". At first, it looks like Black Panther and Hawkeye have failed to rescue the other Avengers, until they reveal they were just buying Ant Man some time to get some stuff from his lab. Then, he gets a Big Damn Heroes moment.
Wasp in "Come the Conqueror" against the scarabs. She found bigger stingers.
Hulk's entrance into the battle against Graviton, and again in the Avengers first fight against Ultron.
Iron Man gets a quite impressive one in "A Day Unlike Any Other". Loki has defeated the rest of the team, and Iron Man comes crashing down through the roof in new armor made of Uru metal.
Thor does an epic one during the climax of the Skrull invasion.
Big Bad Ensemble: Several of the villains have their own agendas, notably Baron Strucker, Baron Zemo, the Leader, Kang, and Ultron. The presence of an overarching Big Bad is built up throughout the season, however, and it's ultimately revealed to be Loki, who was directly or indirectly responsible for just about everything except Kang and Ultron.
Season Two brings us a new crop of Big Bads, each with their own plans: Queen Veranke and the Skrulls, Ultron again, Red Skull, the Kree Empire, and Galactus. Surtur would have been a Big Bad, but thanks to the series' cancellation he never actually fought the Avengers.
Big "WHERE?!": Thor was vanished from Asgard and, unable to return, he asked Tony Stark for help, to see if he could send hm with some technological way. After a long work, Stark and T'challa ended a machine for that. He was so proud of it... but Captain America spoiled his pride. "Not to rain on your parade Tony, but I saw a similar machine do that kind of thing back in my day. It worked, too.
Big "WHO?!": Captain America:So, when will I meet the Avenger that saved me from Zemo? The one in the black catsuit.
"Hail, Hydra!": Black Widow's name has been cleared, at least among the Avengers, and the HYDRA-AIM war has been stopped, but Widow still has to leave Hawkeye behind, much to their despair, and Maria Hill is now hell-bent on pressing the Avengers into SHIELD membership.
"A Day Unlike Any Other": Loki and the other villains are defeated, the Nine Realms are saved, but Cap's shield was destroyed, Thor stays in Asgard, Hank is ready to quit, and Cap is replaced by a Skrull.
"Michael Korvac": The titular antagonist has been stopped, but only after traumatizing and scaring the woman he loves, and even then, he appears to have exiled himself to another plane of existence entirely in a massive Heroic BSOD. What's worse, Peter Quill implies that horrible stories like this are regularly encountered by the Guardians. On a meta-example, the episode was dedicated to Boyd Kirkland - "Friend, Father, Director, Avenger," and the credits played in silence.
Blade Reflection: In "Welcome to Wakanda", Iron Man and the Wasp are reflected in the Grim Reaper's scythe as they advance on him in the mine.
Blasting It out of Their Hands: Hawkeye (who else?) made this one to save Mockingbird, even when he could have killed the Black Widow if he just shot a pair of centimeters to the right. Of course, he did not miss, he's Hawkeye.
When they show a shot of Tony's heart we actually get to see the shrapnel embedded in it.
Zemo and Klaw both have a few seconds showing their bodies being horribly distorted as they transform into monsters. Bruce Banner's transformations into the Hulk are pretty alarming, although at least he gets to shift back... on occasion.
Bond Villain Stupidity: Practically everyone from Hydra and numerous other villains. The worst case probably was in Captain America's first episode, when Red Skull even failed to order Cap and Bucky restrained before going into Evil Gloating mode, even though the (quite vulnerable) device crucial to his plans was in the same room.
Greatly averted with Ultron, Dr. Doom, and the Skrulls, all of whom are very genre savvy.
Boxing Lessons for Superman: As Steve points out (and proves...much to Hawkeye and Hulks amusement), Tony (aka Iron Man) is a very poor hand-to-hand fighter and is rather helpless without his armor. Cap ends up giving him some lessons.
Brainwashed: Enchantress tried to pull this on The Hulk. It ends about as well as you might expect, but she successfully creates a rift with him and the team. It backfires in the long run, since now Hulk seems to have a grudge against her.
The Red Skull does this first to Bucky, making him into the Winter Soldier, and later to Doc Samson and Falcon.
Breaking the Fellowship: After the reveal that Skrulls are on Earth, the Avengers splinter, with Iron Man, Ms. Marvel and Black Panther leaving out of mistrust and fear for the others. All that's left of the official Avengers at the time are Captain America, Hawkeye, Hulk, and Wasp.
And not long after that, Skrull!Cap takes advantage of the Red Hulk's rampage to get Hulk out of the picture, making it a team of three.
Brick Joke: Happens to Hawkeye in the season 1 finale. Hawkeye innocuously punches a random inmate in the episode "Breakout Pt 1." At the end of the season, the man, Chemistro, still has a grudge against him for it and attacks him while Hawkeye's separated from the group.
The Bridge: Kang has one at the Damocles base. Fury has no special "seat" at the hellicarrier, there is such a bridge but he's always standing.
Brought Down to Normal: Happens to Captain America, Thor, and Iron Man in the appropriately titled "Powerless" due to a magic spell. Cap is back to his scrawny, pre-Super Solider serum self, Iron Man is in his prototype armor (which he can't remember how to work), and Thor is a mortal (who gets his leg broken early on).
Happens in "Assault on 42". Kinda. It's actually attacked from the outside by a horde of unstoppable alien insectoids who can eat through metal like it actually is cardboard. The prisoners are actually let out to help fight them off. In fact the prison was soeffective dialogue in later episodes reveals the new Hydro-Base prison is just temporary until 42 is repaired.
Cavalry Betrayal: As SHIELD did not arrive yet, Iron Man fought alone against the dreadnoughts of Hydra outside the United Nations. SHIELD finally arrived and helped him... and tried to take him prisoner (or something like that).
Cerebus Rollercoaster: Granted, the show never seemed entirely fluffy, but the dark themes seemed to progressively increase from "Ultron-5" onward. After the retool, though, the level of darkness became more inconsistent, sometimes reverting to the level from the early episodes.
Also note that season 1 has a Y rating (everyone of all ages can watch), while season 2 bears a Y7 stamp (children six years old and younger probably shouldn't watch).
Characterization Marches On: Averted, with the Hulk. This portrayal owes more to the Hulk as he was originally depicted by Stan Lee and Jack Kirby, rather than as the Psychopathic Manchild the character is most recognizable as. He uses tactics and is capable of outwitting his foes in addition to beating them senseless. Plus, he speaks in complete sentences! And sarcasm!
Also displayed in Hulk's case, in that he shows on occasion he can draw on Bruce Banner's knowledge when he cares to, identifying Michael Korvac's energy emissions as cosmic radiation at a glance in the eponymous episode.
Charles Atlas Superpower: Half the things Black Panther does are. at the very least incredibly improbable for any normal human, if not outright impossible. Witness his stunt in Come The Conqueror: When being fired at by Kang's robots, he's seen avoiding them by running along the side of a building. When he reaches the edge, he jumps backward and bounces off a building on the other side of the street and slashes a robot, ultimately landing without taking any damage.
Justified by backstory; Black Panther, like Captain America, is basically a super powered fighter masquerading as a Badass Normal — the training, skills, ability and intellect of a Badass Normal bolstered by a rare Super Serum herb native to Wakanda and, in some tellings, a mystical connection to a patron panther god.
Chronic Backstabbing Disorder: Played straight in "This Hostage Earth" when Amora stabbed Grey Gargoyle in the back, and then subverted when Zemo betrays her before she can betray him (Which he fully expected).
Cliff Hanger: Cap getting replaced by a Skrull at the end of Season 1.
There's a mid-season one with the U.S. broadcast of season 2 where Nick Fury tells Iron Man his team has been infiltrated by a Skrull, Iron Man, Ms. Marvel, and Black Panther leave the team, and it's revealed that Mockingbird had been replaced by Queen Veranke some time after her first appearance.
Co-Dragons: Abomination and Absorbing Man to the Leader.
Compilation Episodes: The twenty micro-episodes were later compiled into the first five episodes for airing on television.
Fans have taken this a step further, editing all the micro-episodes into a single long movie.
The reverse is true, actually. Disney XD only split the first five episodes into the mini-episodes. Later airings and DVD releases have them as they were intended.
The Complainer Is Always Wrong: Ant-Man's suggestion for the Serpent Society to nonviolently talk out their problems instead results in the battle between them and the Avengers intensifying, much to the frustration of Ant-Man's teammates.
Composite Character: Baron Zemo is a combination of elements of his own comics counterpart (Heinrich Zemo) and his son and successor (Helmut Zemo). Similarly, the Crimson Dynamo is a villain—but wears the suit worn by Gennady Gavrilov, a hero, from the comics and, according to his bio in issue 2 of the tie-in comic, has element of the already-Composite Character of Ivan Vanko from Iron Man 2 (his real name and reasons for hating Iron Man stemming from something that happened between their fathers).
Inverted with Nick Fury, who's actually split into two characters: Jack Fury, Nick's identical grandfather who led the Howling Commandos in World War 2; and Nick Fury, the 21st century super-spy who serves as the director of SHIELD. note In the comics, Nick Fury was both—he actually did serve in World War 2, but Comic Book Time eventually forced the writers to establish that he took anti-aging drugs to explain how he was still alive six decades after the war ended.
Played straight as well. He is black like the Ultimates and Cinematic incarnations of the character but has hair identical to the modern 616 version, at least until the second season, where he looks more like his Ultimate incarnation.
While not a character, Kang's sword-shaped spaceship The Damocles is merged with The Peak, S.W.O.R.D.'s sword-shaped space station.
The Super-Skrulls of the Skrull invasion are composite characters with the combined powers and uniform details of several super heroes (some had appeared, others had not).
Conservation of Ninjutsu: In "Assault on 42", a single bug destroys the base, while hundreds of bugs go down like pieces of meat.
Conspicuous CG: Many examples. The most notable include the Quinjets and the Helicarrier.
Jack Fury: Howlett! We need recon! Wolverine: I'm workin' on it, bub!
HERBIE passes by as Hank Pym and Reed Richards study Princess Ravonna during one of the last scenes of "The Kang Dynasty."
On Nick Fury's board of Skrull suspects there are several pictures of characters that never appeared on the show. These include Cyclops and Beast of the X-Men, the Scarlet Witch, Magneto, Cloak & Dagger, and Armadillo.
Several of the power mash-up Super-Skrulls have the costumes and powers of a few characters that never appeared on the show, including Cyclops, Nightcrawler, Colossus, and Black Bolt.
Continuity Nod: When he's being deactivated and utters random information, the Supreme Intelligence mentions the first alien contact of the Kree, which was with the Skrulls... and even mentions the Cotati. The what? Some kind of Fantastic Flora that lived in Hala along with the Kree, before the Kree destroyed them all (or most of them). The Cotati and the first contact of Kree and Skrull were seen at The Celestial Madonna Saga.
Carol Danvers mentioned that, in the airforce, her codename was "Warbird". In comics, she took the name Warbird during Kurt Busiek's run, and returned to Ms. Marvel during Bendis' run.
Also Zemo taking down Grim Reaper in all of 2 seconds. Now that's skills.
Actually happens quite a lot, with heroes and villains on both ends. One notable instance is Doctor Doom's debut, where he takes down all of the Avengers (minus Thor and Ant-Man) and the Fantastic Four without any trouble at all.
Dark Messiah: Both The Leader and Ultron claim to be "saving" the world. The Leader actually has followers, though.
The Skrulls do this too, with the Skrull-Captain America filling the Dark Messiah role.
Deus ex Machina: Literal example when Thor returns to Midgard (Earth) just in time to stop a Skrull invasion.
Deus Exit Machina: Invoked by the Masters of Evil, who send Hulk to Jötunheimr to fight the Jötun (Frost Giants) so he can't cause a Curb-Stomp Battle. It does keep him out the way, until Thor opens a portal to bring him back, and he stomps through covered in snow, carrying a big ice club, and pissed.
Do Not Adjust Your Set: The Leader sent a message to all the world. It was seen by everybody: Nick Fury, Hydra, Pepper Pots, Henry Pym in Wakanda, the Masters of Evil, a random multitude; even Clint and Natasha in the middle of the desert (the leader hacked SHIELD's private lines as well). Of the characters introduced so far, they missed Jane Foster, the bar in the desert, perhaps Dr. Doom, Kang (his ship is cloaked somewhere up there), and a short shot at the White House would have been interesting.
The Skrulls made a second one, to broadcast their message of conquest.
Does This Remind You of Anything?: Hank and Janet's conversation in "To Steal An Ant-Man" about him leaving the Avengers sounds a lot like a typical breakup talk. Given who we're talking about, this is almost absolutely deliberate.
Dramatically Missing the Point: When Steve tries explaining to Tony why he should learn how to actually fight without his suit, Tony just brushes it off as Steve being too used to the "old ways" of doing things. The fact Steve brutally kicks his ass because he seriously lacks fighting skills doesn't seem to phase him, either. Tony just assumed he doesn't need to know how to fight, because his armor will handle any problem. It doesn't seem to occur to him that adding even basic fighting skills to the power provided by the Iron Man armor would make him that much more effective.
Dual Wielding: Some of Kang's armory includes two glowing swords that he wields with surprising skill, even going toe-to-toe with Captain America.
Not too surprising, since Kang (like his thematic opposite, Captain America) is a One-Man Army. Kang (or at least his Marvel Comics analog) visits other times and dimensions and devastates entire planets not For the Evulz but to perfect his art.
Sif and Zemo also fight with a set of paired blades.
DVD Commentary: The final volume of Disney's DVDs has at least one commentary performed by the voice actors of Iron Man, Captain America, Thor, and Hulk, in character.
Dysfunction Junction: The team has some issues to work out. Noted in-series by Ant Man, who acknowledges that a group of people who are essentially strangers won't initially act like a team. Later, Hawkeye rants to Black Panther about how the other Avengers are completely unsuited for superheroics (though to be fair, a couple of his critiques are flat out wrong, and as Panther points out, he didn't say a thing about Captain America).
Early-Bird Cameo: Crimson Dynamo, Technovore, and MODOK showed up in "Nick Fury: Agent of SHIELD".
There are several in the Hulk micro-episode, "This Monster, This Hero", as well. Villains seen in The Cube include Bi-Beast, X-Ray, Vector, Vapor (three of the four members of the U-Foes), Abomination, The Leader, and Radioactive Man, among others; most of these returned in "Gamma World". In the earlier episode where the Hulk fought Absorbing Man, Mr. Hyde appeared when Banner was talking about the Cube. Also in the Hulk micro-episode was SHIELD agent Morse, who returned in "Widow's Sting" as Mockingbird.
In "Meet Captain America", we meet James Howlett, who most fans know as Wolverine.
Earn Your Happy Ending: The series finale has the Avengers being cheered by the public for defeating Galactus, showing that people care for them again after everything that happened with the Skrulls.
Easily Thwarted Alien Invasion: The Skrull Invasion, for all the buildup, consist of a single space ship, a few hundred Skrulls at best and a dozen or so Super-Skrulls. The loss of a single battle against the Avengers and return of Thor is all it takes before the Skrulls try to kill every one on Earth. Many of the other villains with far less resources did much better at conquering the world.
Elite Mooks: Kang's three elite guards on Damocles Base gave the Avengers a run for their money, thanks to help from their boss's time-controlling powers.
Except that it was obvious almost immediately that their only advantage was their boss's time manipulation technology, allowing them to make Time Stand Still around themselves and perform a Speed Blitz on the Avengers. Once Hawkeye's flare arrow blinded the mooks and impaired their ability to react to their opponents, the Avengers defeated them easily.
Enemy Mine: Subverted; Hawkeye adamantly refuses to work alongside Black Widow again no matter how desperate the situation.
That was later subverted again, when he actually did, although technically she wasn't a villain.
This is played perfectly straight in "Acts of Vengeance" when Zemo, Abomination, Wonder Man, and Crimson Dynamo join forces with the Avengers to fight off the wrath of a vengeful Enchantress and Executioner.
It was done again in "Prisoner of War", with Captain America, Mockingbird, Invisible Woman, and Agent Quartermain teaming up with Madame Viper, King Cobra, and an A.I.M. agent named Dr. Lyle Getz in order to escape from the Skrull ship.
Happens yet again in "Assault On 42", when Annihilus and his Annihilation Wave invade Prison 42, the Avengers are forced to release many of the imprisoned supervillains (and Captain Mar-Vell) to help fight them. Captain America, however, refuses to let out Zemo, knowing that he'd just stab him in the back.
During the Skrull invasion, Doctor Doom gives Tony a piece of tech that can help detect and reveal Skrulls. However, he finds it beneath him to actually join the Avengers in battle, and prefers to let them do all the dirty work.
End of Series Awareness: "Avengers Assemble" begins with Tony asking Steve if he ever wonders how the Avengers will go down in history, prompting this exchange:
Steve: This is only the second time I've heard you use the word, "history."
Tony: That's because I've never been able to imagine a world without me in it...until recently.
Also, the last line said in the episode (and the show) before the fade to the show's logo.
Captain America: You wanted to know how history will remember the Avengers, Iron Man? Well, here's your answer.
Enhanced on DVD: When "Masters of Evil" first aired, the final scene looked so dark, the viewers couldn't see Loki's face◊. This scene became brightened◊ in the version shown on Netflix. The producer confirmed here that the broadcast version obscured Loki because of post-production and video transferring errors, not because of a stylistic choice.
The difference becomes more visible when viewing the monitor from a certain angle.
Thor: "Tis surprising how many monkeys we face in battle."
Evil Gloating: When Sue Storm and Wasp get kidnapped, Wasp tries to piss off their captor by talking crap at him. Unfortunately, her captor's Doctor Doom, so it doesn't work.
Doctor Doom: "Miss Van Dyne, I am not some common criminal that can be distracted by your prattling. You are nothing to Doom, and your pathetic attempts to play mind games with me amount to exactly less than nothing. So please, stop embarrassing yourself."
Evil Versus Evil: The Kree-Skrull conflict, wherein whoever wins, humanity loses. Both of the sides are known for conducting painful medical experimentation on those they capture and go around the galaxy wiping out or enslaving other planets/species. The Kree are supposed to be the "good guys", given their self-designated role of judging other species, and it helps that two heroes featured in the show are Kree. Conversely, while the Skrull are supposed to be the "evil" side (and are more malicious in behavior), they have a sympathetic backstory (Galactus ate their home planet), and favor enslaving humanity whereas the Kree favor exterminating it.
Evolving Credits: The team shot at the end of the opening titles varies depending on the size of the team at the episode's start.
Additionally, the Earth's Mightiest Heroes logo at the intro's close originally had an empty circle underneath it. During the second half of the first season, the circle became replaced by a variant of the Marvel Cinematic Universe's "Avengers Assemble" emblem.