Faceless Goons: Kobra's masked cultists, Black Manta's helmeted manta troopers, and Queen Bee's balaclava wearing soldiers.
Averted a few times though, once Artemis infiltrates Black Manta's crew.
Fake Defector: Aqualad, who joins Black Manta in order to learn the secrets of the Light during Season 2.
Double Agent: Discussed in "Darkest", where after Aqualad fakes Artemis' death, kidnaps 4 members of the Team and blows up Mount Justice, a guilt-ridden Kid Flash begins questioning if Aqualad is actually a triple agent who really has gone bad.
Fake Static: Lagoon Boy does this over the psychic link. Nightwing immediately calls him on it.
Faking the Dead: Artemis in "Depths," who is being sent undercover to infiltrate the villains. Only Nightwing, Aqualad and Wally know the truth, and the episode "Satisfaction" shows her mother crying at her grave, her memorial in the cave, and her sister and father swearing vengenace.
Joker gas is released from a giant plant, gassing three firefighters who fall down and die onscreen. They probably got away with this because it's never explicitly stated that Joker gas kills people, but come on, it's The Joker.
Joker basically says it's deadly when he says none of them will be making it out of the bayou and activates the joker gas.
In "Failsafe", the alien invaders disintegrate numerous civilians, the entire Justice League, and half the main cast on screen.
Family-Unfriendly Violence: Black Beetle repeatedly bashing Wonder Girl against a wall for just over 10 straight seconds of airtime. Chilling, and frankly surprising that it got past the censors.
Fantastic Drug: Luthor's "shields" suppress human DNA to allow a half kryptonian to use the full range of their powers. In practice they function more like G-rated steroids.
When talking about race conflicts in class, Megan mentions to Conner that on Mars there is a lot of discrimination against the white minority by the green majority. It turns out that Megan is really a white martian, who takes a green and more humanoid form to avoid ostracization on Earth.
In season two, reporter G. Gordon Godfrey is trying to encourage this by suggesting that the Justice League may be harboring more aliens than the publicly accepted Martian Manhunter and Superman. It works.
The tie-in comic has a story revolving around a group of Atlantean extremists who try to incite violence against the citizens who do not look fully humansuch as Lagoon Boy, or even Kaldur himself, who has visible gills and webbed digits. In a later issue, La'gaan tells M'gann that he came to the surface in order to escape such prejudice, same as she did.
In "Auld Acquaintance", Superboy throws Robin at mind-controlled Batman.
In "Alienated", Superboy asks Superman for a "triple combo", which starts with Superman throwing him at a Spider Tank. He jumps off it, hits another one, jumps off that one to take out a third, then lands and punches out a fourth one.
Feuding Families: Black Manta and Sportsmaster's families following Artemis and Kaldur faking her death.
When Robin, Aqualad and Kid Flash go to investigate the Cadmus lab in "Independence Day", Cadmus immediately wants to clone the three sidekicks and then send the clones off as moles back to the League. We later find out that is actually what happened to the real Speedy three years before the series even began. He even refers to it as "the new Project Sidekick", indicating there was an old one.
When Dubbilex reveals his complicity in bringing the sidekicks to Cadmus he refers to the Genomorph clones as "brothers," and the camera lingers on Guardian. His later assertion that he is Speedy/Red Arrow's uncle makes his connection to the previous Project Sidekick obvious.
When Red Tornado confronts Mister Twister in "Welcome to Happy Harbor", one may notice that Tornado is flying without using his air powers and that his whirlwinds are white instead of red. When Mr. Twister tries to brainwash Red Tornado, it's turns out that it was Miss Martian disguised as him and that Kid Flash was providing the whirlwinds.
In "Downtime", Aqualad wears manta trooper armor and Black Manta calls him out for blindly serving Aquaman. Come Season 2, Aqualad has joined Black Manta, his father, the secret of which was kept a secret from the young Atlantean. Except Aqualad's a Fake Defector and it's all part of Nightwing's plan to take down The Light.
In "Targets," Sportsmaster reveals to Aqualad that he has an "inside source" on the Team, before it shows a close-up on his eye and the camera moving from Aqualad to Red Arrow.
Mercy's cybernetic arm is foreshadowing for Arsenal getting a similar arm in "Satisfaction", after his organic arm was amputated to clone him.
Several times, for Miss Martian's true nature as a copycat of a sitcom character and as a White Martian.
Episode 16 contains several pieces of foreshadowing for the second season: the alien invasion premise, what happens to Artemis, Kid Flash's reaction, the depths of M'gann's true power, Robin's leadership style.
After Impulse lists off the present team members early on "Bloodlines", the only other person he specifically mentions and expresses interest in is Blue Beetle. He also uses the words "crash" "mode" "meat", which are later terms used by the Reach.
When Virgil is talking to Black Canary, he plays with a paper clip. When he walks out, he drops on the desk, and it magnetizes and drags the rest of the clips together in a ball.
Robin twice uses escrima sticks to help him fight, once against the MONQIs and once again in the season finale. Come season two, he's graduated to being Nightwing, who keeps his escrima holstered on his thigh and reaches for them much more readily.
Kid Flash's stealth costume is black, reminiscent of the "Black Flash", a kind of Grim Reaper for DCU speedsters. He dies in season 2.
The Fourth Wall Will Not Protect You: The first season finale reveals that the trigger phrase to activate the mole is "Broken Arrow," which puts Red Arrow into a trance where his handler can retrieve information and plant subconscious instructions. This phrase also works on the audience: After it was uttered, the show cut to a commercial and returned after the counter-command was given, leaving the audience unaware of what had transpired, and ignorant even of the fact that anything had happened at all.
In "Welcome To Happy Harbor", the camera rests for a second on the Team's screen tracking Red Tornado. If you have an HD tv you can freeze it and make-out most of RT's file detailing the Elemental Wars. This was actually unintentional and upset Greg Weisman—somebody decided to put that in for this trope, but did not realize that the Elemental Wars have not happened yet (if they will at all) according to the Universe Bible.
In "Downtime", you can read the rigorous screening process of Gotham Prep in Artemis' acceptance letter. The letter also reveals that her full name is "Artemis Crock", which has yet to be conveyed through dialogue.
In "Bereft" there is a split-second shot of a White Martian (which could've easily been mistaken for a Cadmus genomorph in Superboy's memories) while M'gann is restoring the Team's memories. Doubles as a Chekhov's Gun: in the episode "Usual Suspects", Superboy reveals he saw it, too.
An accidental one happens in "Beneath". A map of Bialya depicts the nation as encompassing the territory of Qurac, suggesting that Bialya successfully annexed its neighbor over the timeskip. Word of God says this wasn't intentional.
Gar's room in Mount Justice. Right before it's destroyed by a bomb, hence the freezing. On his wall, he has posters of Hello, Megan! and Dick Grayson's Robin, and a picture of his mother on the dresser.
"Before the Dawn" is just the beginning as M'gann breaks Kaldur's mind, Artemis is trapped on The Light's side with her only ally broken, The Reach formally introduced themselves to the world before the Justice League could warn the public, and they have an entire armada waiting in the Mariana Trench till the day they can make their move and begin a conquest.
"Runaways" didn't help matters, with Blue Beetle being revealed as back on mode, the Green Beetle turns out to be a Reach agent, and the Runaways unwittingly joining up with Lex Luthor. All of this with no knowledge from any else related to the Team or the Justice League.
Word of God says that it's gonna keep getting worse throughout Season 2.
Fun with Acronyms: Robot monkeys? Why they are Mobile Optimal Neural Quotient Infiltrators. Ivo even lampshades it when they get destroyed.
"And after all the trouble I went through finding an acronym for monkey."
Future Me Scares Me: A case where the somebody doesn't actually meet their future self, just hears about it, when Jaime is told that in the future, Blue Beetle is the worst villain of all, he fights very hard to avert it, and is plagued by images of an evil him.
Futureshadowing: When we see Impulse's future, he's working on the time machine in the hollowed out portion of a destroyed Mount Justice. Which happens about three episodes later.
"Beneath," where Nightwing uses Queen Bee's ability to control men as a justification for Alpha Squad consisting of the all-female Miss Martian, Bumblebee, Batgirl, Wonder Girl and Bio Ship. Batgirl calls Nightwing on the implied sexism— and the last time Dick explained Bee's powers that way, Batman called him on the heteronormative implications.
Gender Flip: In the Red Tornado miniseries, Red Torpedo is female and Red Inferno is male. The animated versions have this reversed, to fit the Golden Age characters they've been combined with.
Asami "Sam" Koizumi is a female version of Samurai from Super Friends.
Genre Savvy: In "The Runaways", Red Volcano takes the titular group hostage and then tells Blue Beetle to do the typical "save the hostages and let the villain escape" move.
Wrong Genre Savvy: Blue Beetle uses a Chest Blaster to send Volcano flying while the runaways free themselves, even telling Volcano not to stereotype. This foreshadows the fact that Jaime isn't the one in control.
"Secrets," where the male characters (and M'gann) are either at a school dance or meeting with members of the Justice League, leaving Zatanna and Artemis to spend the night fighting crime in New York City.
Glamour Failure: Played with in "Disordered". M'gann suddenly changes into her human appearance during her therapy session, causing her to flip out when Black Canary points out that she just turned "white"; she calms down when she finds BC meant "Caucasian", as opposed to a White Martian.
Glass Cannon: The alien scouts in "Failsafe" can disintegrate Superman in one shot, but can be taken down by one of Artemis's arrows.
A Glass of Chianti: In "Alienated", Black Manta is seen in his private quarters, eating a fine meal and sipping wine.
Godzilla Threshold: Using the Helm of Nabu transforms the wearer into Dr. Fate and grants them the power of a Lord of Order, but Nabu is not that keen on letting the one wearing it have their body back.
When Aqualad feels that he and the Team cannot defeat the Injustice League, he becomes Dr. Fate. Kent Nelson talks Nabu into backing off.
In "Misplaced", Zatanna decides use the helmet again. This time, however, Nabu is tired of the run-around and has no intention of releasing her. He even sent Nelson off to the afterlife when he tried to protest. Zatara has to offer himself as a replacement to free her, and he is not going to be removing the helmet.
Gondor Calls for Aid: In the second season finale "Endgame", every hero introduced up to that point (except for the ones on Rimbor and the ones that died) can be seen at the debriefing for the Reach's endgame, helping save the Earth.
Gone Horribly Right: T.O.Morrow's fourth android, Red Volcano, was built with the express purpose of not having any heroic programming so that it would not be bound by morality or humanity. Red Volcano, since it had no humanity or morality, killed Morrow as soon as it was activated.
Good Guns, Bad Guns: Inverted in the case of oppressive Bialya and progressive Qurac. The former's military uses equipment drawn to resemble Real Life American military equipment, while the latter's soldiers use Kalashnikov-like guns.
Good Is Not Nice: Nabu, a Lord of Order, is one of the world's most powerful protectors and one of the only defenses against the Lords of Chaos, but to affect the world he must inhabit the body of a mortal. If he cannot find a willing host he will take one, and if he fears that his host cannot be trusted to don the Helm of Nabu after they have been freed, he will never let them go.
Good Parents: Wally's. Also, surprisingly, Batman, whose relationship with Dick is better than in most modern continuities.
Gratuitous Greek: In "Downtime", the conversation between Aquaman and Aqualad is spoken in very bad Greek. Word of God is that it was supposed to be a dialect based on ancient Greek, which might explain why it sounded jarring to modern Greek speakers.
Gravity Is a Harsh Mistress: Captain Marvel has a Gravitational Cognizance moment in "Misplaced". When he transforms, shifting himself from the kid dimension to the adult one, it takes a few moments for him to realize that the plane he was in has not made the trip with him.
In season one, the male members of the Team are either straight hand-to-hand combatants, or include hand-to-hand with their weaponry. The female members of the Team, however, have telekinesis, a bow-and-arrow, magic and technology gadgetry so they do not need to physically touch their opponents.
Averted in season two, where the first episode introduces Wonder Girl and Batgirl, two hand-to-hand combatants that serve as some of the members of the newer Team.
Hacked by a Pirate: In season 1, Robin's hacking skills is always represented by a chibi Robin on-screen either frowning (in the process of hacking) or grinning (hack complete).
Hammerspace: In the fight with Harm in "Secrets" just where does Artemis' crossbow come from, or dissapear to a few moments later?
Helping Would Be Killstealing: Red Tornado wants the Team to solve problems for themselves rather than have to have the League come in when things get hairy, explaining that it is a part of their training and a natural outgrowth of their demand to be treated as equals.
Heroes Want Redheads: Played with. The redheaded Kid Flash has a crush on the equally redheaded Miss Martian, but she likes Superboy and doesn't show an interest in Kid Flash. Aqualad has feelings for Tula, his friend from Atlantis. Ultimately, blonde heroine Artemis falls for red headed Kid Flash.
Heroic BSOD: The Team spends "Disordered" in one. Except Conner, who's busy kicking ass.
In "Before The Dawn," Miss Martian goes totally blank after pulling a powerful Mind Rape on Kaldur, not realizing he was good all along. She remains nearly unresponsive for the rest of the episode, only vaguely paying attention to what's around her and not putting her head into anything.
When Wally's body risks being taken from him to act as a vessel for Dr. Fate, Kent Nelson gives up his chance to Ascend to a Higher Plane of Existence and reunite with his wife so that Wally can keep his body and find a more suitable vessel for Dr. Fate.
Red Torpedo's and Red Inferno's death by melting in a volcano to restrain Red Volcano, in order to save humanity.
Aqualad, Superboy, Robin and Kid Flash to save Martian Manhunter and stop the enemy attack in "Failsafe".
In "Misplaced", Zatara sacrifices himself by becoming the new Doctor Fate so Zatanna, his daughter, doesn't have to.
in "Endgame" Wally does it again helping the other Flashes try to stop black beetle's apocalypse plan. He didn't get better.
He's Just Hiding: Wally's in-universe reaction to Artemis and the rest of the Team's deaths in "Failsafe", because he thinks the beams are just transporters.
Hot for Teacher: Kid Flash, in true Flash style, starts to flirt with Black Canary as soon as she appears as the Team's combat trainer. He does this again as a defense mechanism when she mentions Artemis' "death" in "Disordered".
Hour of Power: Superboy's "Shields" last about an hour before burning out.
Hypocrite: The oh so compassionate and moral Superman who supposedly inspires everyone to be better refuses to show any compassion towards his clone Superboy during the first season.
Hypocritical Humor: Dr. Fate, having possessed both Kid Flash and Aqualad at different points, supports their candidacy when the Justice League is discussing new members. Then they bring up Zatanna, whom he has also possessed, and he quickly refuses. He is immediately called on still having Zatara's protective instincts.
In season 2 episode, "Satisfaction", Miss Martian says that "She can't focus on parties"... while going to Rocket's bridal shower.
I Am Not Spock: Marie Logan, the star of the teen sitcom "Hello Megan!" and who now runs an animal reserve. Miss Martian based her whole personality and appearance as a human on her. When Miss Martian starts pestering the now older Marie with questions about the show she insists that it was just a job and that Megan "is not who I am."
I Gave My Word: When Zatara offers himself as an alternate host, Nabu asks what guarantee he has that he won't just put the Helmet of Fate back on a shelf when it's removed. Zatara simply responds, "My word." Nabu accepts this, and Zatara is true to his word, putting on the helmet and becoming the new Doctor Fate.
Ignored Expert: The Reach's head scientist really wants to find out how the Blue Beetle went off mode for the last 4000 years, but Black Beetle and the Ambassador are not interested. As a result, Blue and Green Beetle were freed from the Reach's control. Her last appearance is full of I Told You So.
I Have a Family: Said word for word by one of the female guards in "Terrors".
I Know Madden Kombat: Robin I/Nightwing and Batgirl. Word of God notes that the fight choreography tries to reflect their backgrounds as an acrobat and a gymnast, respectively.
I Let You Win: Queen Bee's minions deliberately throw the fight against the Team in "Intervention" because it serves the Light's purposes to have them free Blue Beetle from Reach control.
I Shall Taunt You: Both Robin and Kid Flash are the "chatter until the villain gets pissed off" types.
When the Runaways get teleported right in the middle of a squad of Reach soldiers, they pretend to surrender so they can catch the soldiers off guard.
I Take Offense to That Last One: In "The Hunt", Arsenal, upon seeing Lex Luthor communicating with the Runaways, deduces that he used them as a distraction so one of his pawns could steal the WarWorld's key. Lex insists that Deathstroke is really more like a bishop than a pawn.
I Was Just Joking: When Wally sarcastically asks which team member has a dramatic revelation to share with the rest of the Team next, he is shocked when M'gann steps forward.
An Ice Person: The opening scene of the first episode involved several independent ice-themed villains (Mr. Freeze, Icicle Jr., Killer Frost and Captain Cold) attacking separate cities at once. The League considers this an unlikely coincidence and worth looking into. They were planning to be incarcerated together in Belle Reve Penitentiary to engineer an escape with the entire inmate population.
Identity Amnesia: When Psimon erases six months worth of memories from the Team's minds in "Bereft," Superboy is left without any memory, since he'd only existed for six months. Hence, he became a wild-eyed, shirtless Berserker.
In season 2, Robin, Artemis, Kid Flash, and Aqualad don't tell their telepathic teammate of their ruse to fake Artemis' death, knowing full well that Miss Martian is likely to run into Aqualad at some point. This backfires badly when she mindrapes Aqualad, leaving him a vegetable.
Season 2, "True Colours" Arsenal blows up the LexCorp Farms for no real reason. He says he's mad at Luthor, but the actions inconvience them more than Luthor and if he really wanted to blow it up he could have waited until they escaped.
Robin, as well for not telling Nightwing what happened.
Incredibly Lame Pun: It sometimes feels like every other line from every other villain is a terrible pun about their own name. Main offenders: the Light, Harm, and the Reach.
In Spite of a Nail: Impulse curing Neutron in "Bloodlines" just turns his Bad Future self into a normal human and removes some of the fallout. Everything else remains the same. This is the first hint that Neutron isn't directly responsible for said future.
Informed Ability: Most of the team speak several languages according to Greg Weisman. Unless this is plot-relevant, it doesn't get brought up or used. It's given a nod in "Drop Zone", when Superboy listens to Bane and a Mook argue in Spanish and quietly smiles.
Ink-Suit Actor: Professor Ivo bears an eerie resemblance to a red-haired, slightly older-looking Peter MacNicol in a sweatervest.
Inner Monologue: Miss Martian briefly had an inner monologue in "Bereft," where she thought in Martian because she did not remember that she had traveled to Earth. It was only after she deduced where she was that she began thinking in English.
Insecurity Camera: Played with in "True Colors". Alpha Squad hacks the camera in Luthorcorp Farms with ease. After Arsenal sets off an explosion, however, Luthor monitors the feed and snarks about the obvious disconnect between the visual and the ruckus before having Mercy change frequencies to correct it.
Played straight in the season 1 finale. Anyone hit with the cure tech drops like a stone.
Subverted in "The Fix". Artemis hits Psimon with a dart designed to render him comatose for several weeks, but underestimates how long it would take to kick in and gets slammed around for at least a minute before he finally drops.
Interspecies Romance: Miss Martian and Kryptonian-human hybrid Superboy, followed by her and non-human Atlantean Lagoon Boy. Deathstroke even calls it such when he interrupts the latter pair in "The Fix".
In the Blood: Cheshire jokingly says this of Lian Harper when Roy expresses concern that his daughter seems to enjoy watching them beat the crap out of bunch of mooks.
In "Drop Zone", when Robin first sees the Kobra leader he says "What's wrong, Koby? You look disconcerted." Later in the episode when he proves to be a better fighter than Robin he says "What's wrong, boy? You look disconcerted."
T.O. Morrow has created three separate androids that he hoped would help him destroy the superheroes of the world, but each one chose to be a hero and attempt to become more human. His fourth android, Red Volcano, he made with the express intention of "No more Pinocchios..." Such were Volcano's words to Morrow right before killing him.
When Harm is fighting Artemis, he says "So unfocused. It can't fight Harm while fighting itself." After his Villainous Breakdown, Artemis returns the sentiment.
Dr. Fate beats Klarion by attacking his familiar. When Kid Flash tries this during their second meeting, Klarion morphs his familiar into a giant, super-strong cat monster that can more than handle itself in combat.
Batman defeated Clayface in his first appearance with electric batarangs; when Robin tried it again in Clayface's second appearance, Clayface explained that that trick did not work anymore. It is a good thing the Team knew that and were only using the batarangs as a distraction.
In story at least, the scarab charm. It cured Blue's Scarab in the distant past, but in the present it broke after curing Jaime and Green Beetle. If they get put on mode again, it'll be permanent
It's All About Me: Sportsmaster is not angry that Aqualad killed Artemis, his daughterper se, but he is angry that Black Manta did not ask his permission first, since now it makes him and Cheshire look like "punks."
Journey to the Center of the Mind: Miss Martian breaks Kaldur's mind not knowing that he's a Reverse Mole. In "The Fix", she is forced by Black Manta to heal him, so she and Artemis(disguised as Tigress) enter Kaldur's mind which is shown to be shattered by her attack.
Just Between You and Me: Subverted by Vandal Savage in the first season finale. He goes on a Motive Rant to Black Canary, Red Tornado, and Red Arrow, but he never actually gives any specific details about his plans.
Kangaroo Court: The Tribunal cares more about getting paid off than they do about a fair trial. When the Rimbor 6 are arguing their case, a Kroletean in the audience expresses surprise that the defendants haven't bribed their way to innocence already, and Vandal Savage later admits to offering the Tribunal a hefty bribe for a guilty vote. Even when delivering the verdict, they take a moment to try to coerce a bribe out of the defendants one last time. After the Team delivers evidence that proves them innocent, they still want a bribe. Conner and Ms. Martian eventually stoop to claiming that voting in their favor will be good publicity for the Tribunal, thus leading to future bribes. Thems intergalactic politics folks.
Karma Houdini: As a result of the fact that The Bad Guy Wins, Vandal Savage, Lex Luthor, Queen Bee, and Klarion all get off in as good or better a position than they started the series. Ra's Al Ghul will probably be just fine as well.
Among the "heroes", M'gann has been using Mind Rape left and right, even on Superboy. This has never been publicly revealed, she has shown no remorse (for any of the victims save the ones who are her friends) or indication that she's going to stop, let alone atoned for those she destroyed. At the end of the series, it remains a secret, and Superboy looks like he's going to rekindle their relationship. What the hell?
She does however appear to show reluctance to read Green Beetle's mind a few episodes later, obviously affected by what she did to Aqualad. It may just be that Superboy realised she had learned her lesson.
Kid Hero: The creators have promised that there will be some deconstruction of this trope on the show, especially in regards to Robin.
Kid Sidekick: Aqualad, Kid Flash and Robin, the three founding members of the Team. Being seen as just a sidekick is be a big theme in the show, and each of the Team's members has an adult counterpart in the Justice League that serves as their mentor, role model or inspiration.
Guardian is also revealed to be a victim of this. He gave up the hero identity in response.
Killed Off for Real: Kent Nelson a.k.a. Doctor Fate. His spirit did reside in the Helmet of Fate for a while, but Fate eventually got tired of his nagging every time someone used the helmet and sent him off to the afterlife.
Wally while helping save the world from the Reach's endgame.