Donny Vermillion: is he a Dominion stooge, or a jaded news anchor covering for his recklesslyidealistic younger co-worker, Kate Lockwell? Either way, the fact that he suffers a nervous breakdown after learning that Mengsk was behind the invasion of Tarsonis and is thus indirectly responsible for the death of his brother (who was living/working there at the time), as well as dropping his praise of the Emperor if "Media Blitz" is completed before other missions, such as the Colonist missions, shows he's more than just a mindless supporter of the establishment.
Horace Warfield: while Warfield is seen by many as a decent man and officer, it contrasts greatly with his decision to serve Arcturus, especially following the revelation that Arcturus lured the zerg to Tarsonis. Was he a good man who served an evil master, or is he hiding greater and darker secrets?
Annoying Video Game Helper/Unwanted Assistance: Egon Stetmann keeps giving advice in "Belly of the Beast" that you really should know by now, considering it's the second to last mission (Don't let Banelings get too close. Their acid splash is really nasty). It's even annoying to the characters in-universe; Tychus promptly tells him to shut up.
Anvilicious: The UNN clips are very un-subtle Take Thats against certain TV news organizations and personalities.
The game script contains this line, said by a freed Dark Templar in "Maw of the Void":
"Truly you bring freedom to all, friend Ray-nor"
Big-Lipped Alligator Moment: The Laser Drill from "The Dig" is this. Like it's name suggests, it's a massive stationary drill-like weapon that fires a giant laser beam at whatever it's targeting. In the mission, it's used to open up the door of a Tal'darim temple in order to steal away one of the Artifact fragements. However, the player is also able to operate it manually to fire upon any enemy unit or structure. Even melting high-health units and structures within seconds. Why is it a Big-Lipped Alligator Moment? Because it's the only time the Laser Drill ever appears. A weapon this powerful would surely be useful in any battle throughout the Starcraft II story campaigns, and yet no one seems to realize just how powerful this one-off drill actually is.
"Cutthroat." The first objective is to collect 6,000 minerals before your opponent who has four bases. However, even on Brutal difficulty his defenses around the three auxiliary bases is light so you can steamroll them, all but halting his collection and giving you his mineral fields, in addition to the fact you can just collect scrap scattered around the map to make the money. And once you get that objective you're rewarded a full second base with pretty much every building you could need except Starports, including two Barracks and two Factories, and a full army of mercenary-type units that have increased health and power compared to their normal counterparts.
"Maw of the Void" actually encourage you to take your time building up a huge force of nothing but Battlecruisers and then steamroll the opponents from one side of the map to the other one objective at a time. The fact that your base is on an island also ensures that the only assaults you'll face are from enemy air units and transports.
Also, "Whispers of Doom." In the midst of some fairly intense Terran missions, you get to play what is essentially a Protoss tutorial level.
"Engine of Destruction" gives you Tychus as the most powerful unit in the entire game as the Odin, a proto-type Super Thor. You can't command Tychus directly but he'll try to take out five enemy bases all on his own, and as long as you send a few SCVs and Science Vessels to repair him along the way he can do it too. Later on you'll want to send a squad of anti-air units when he faces Battlecruisers, but overall you can mostly take it easy.
Can also double as That One Level on higher difficulties due to the nature of having to rush your base building just to keep up with the Odin.
"Media Blitz" is pretty easy, as well. Even on Brutal difficulty, you can use the Odin to singlehandedly wipe out one of the three bases and much of a second during the "surprise attack" phase. Once the regular phase starts, a repaired Odin can singlehandedly wipe out the remaining base with little to no micromanagement. With the bases destroyed, there will be no attacks anywhere until you try to control the beacons to broadcast the signal.
Broken Base: You have the Dominion returning at the start of Wings of Liberty as the ruling Terran faction of the sector...despite their numerous defeats that were handed to them throughout episodes V and VI of Brood War. Was it justified that the Dominion was given four years to rebuild? Or was their faction steamrolled too far to a point that they should have been gone for good, or at least reduced to a much smaller faction, and have someone such as the Kel-Morian-Combine, or the Umojans, come in and take over as the Terran rulers?
Crosses the Line Twice: Donny Vermillion is a complete Jerkass; "Up next, a Vermillion commentary: refugees, are they really our responsibility?" However, he's such a complete jerkass that he loops back around to being funny for it, the parody elements notwithstanding.
Not precisely music, but the metal riff that plays when things get serious (the beginning of the The Dig campaign, when Tosh's Specters are released from New Folsom) is pretty dang awesome.
Designated Villain: The Tal'darim. They accuse Raynor of invading planets sacred to them and defiling ancient shrines and temples to steal their holy relics, and he is, and is doing so pretty much just to make money selling those relics to the Moebius Foundation. The next two parts of the trilogy reveal the Tal'darim are an Apocalypse Cult that worship Amon, justifying their stance as villains much better.
Ensemble Darkhorse: Karass. Generally considered to be "like Zeratul, but as a High Templar".
Similarities in name and nature lead to speculation that the Dark Voice was the same being as "The Voice in the Darkness" in the graphic novels. Blizzard has shot this theory down.
Because of Matt Horner's close relationship with Raynor and the fact that they were both part of the Sons of Korhal only to leave following the fall of Tarsonis many have erroneously drawn the conclusion that Horner is the Magistrate from "Rebel Yell." His official backstory, however, contradicts this, though the Magistrate did exist according to The Queen of Blades, where it's stated that he joined the Sons of Korhal prior to the infestation of Mar Sara. Furthermore, Raynor briefly mentions the magistrate in conversation. Apparently, they parted ways after the events of Brood War and Jim hasn't heard from them since.
Foe Yay: Between Tosh and Nova. According to the graphic novels, she and Tosh shared their first kiss with each other, and both of them enjoyed it. In StarCraft II, Tosh has slid down the cynicism side of the Sliding Scale of Idealism vs. Cynicism while Nova completed her Ghost training and was resocialized.
This 2008 video and its derivatives splice the Marine suit construction sequence from the teaser with the mundane outer workings of the barracks before showing the Marine being rapidly slaughtered by zerg. Funny in its execution, but come retail release, it turns out Tychus, the Marine from the cutscene, does get killed, except by Raynor's hands.
Remember how Egon commented in the notes for the automated refinery that the protoss may not have thought of the same thing due to their "religious superstitions"? In Legacy of the Void, it is revealed that the Khala had an ill intention in its inception: to bind protoss to Amon himself.
Firebats can be upgraded with Juggernaut Plating, a permanent buff that gives them +2 armor. In tandem with normal upgrades and Medic support, not to mention their HP has been doubled since the original game, and Firebats can hold off an almost infinite number of Zerg. Add in the other upgrade, which boosts the area of effect of their attack, and they become Zergling mulchers that are nearly impossible to kill. The amount of Game Breaker inherent in this is best summed up by the fact that a handful of Firebats, with one or two Medics per squad and perhaps a single Siege Tank or Bunker as backup, can hold the line against a numberless horde of Zerg units indefinitely during the "Outbreak" campaign mission, to the point where even attacking during the Night phases of the mission, which provokes even larger hordes to spawn, cannot break the line.
One of the Terran upgrades gives all units with energy +100 max energy and +100 starting energy. Battlecruisers now spawn with Yamato Cannon fully charged, at max energy can fire two blasts without waiting, Banshees and Wraiths can go on cloaking missions right away, and Medics and Medivacs can support troops out the door.
Science Vessels. You have to give up the Raven to unlock it from the Laboratory terminal, but it's not really a hard decision — after all, what's the loss of micro-heavy shuttles suffering from Accent Upon The Wrong Syllable which rely on auto-turrets to fight for them when you can mass-produce shuttles which can repair mechanical units and structures using nano-technology as if they were medivacs healing marines, removing the cost of resources for repair work?
Reapers are hilariously broken against the Zerg, thanks to their very high mobility and high damage against small units and buildings. Using Reapers to out-Zerg Rush the Zerg is intensely satisfying. Oh yes, and one of their campaign-exclusive upgrades gives them a damage and range bonus.
Goliaths start out Overshadowed by Awesome when you first get them, only being useful for Anti-Air, which is still a niche use. However, their campaign upgrades not only boost the range of their Anti-Air attacks, but allow them to attack ground and air units at the same time. Combine this with boosts to their attack and armor from the Armory and a small army of goliaths can wade into mixed-unit enemy war-parties and usually come out on top, though especially if they have SCVs on hand to repair the damage. Once you unlock their mercenary counterparts, Spartan Company, there's little reason on lower difficulties not to just amass an army of goliaths and send them into the fray.
For a less obvious, yet still massive Game Breaker, there's Tech Reactors. Combine the mass-production of reactors with the unlocks of Tech Labs in one addon. This lets you churn out 2 of any unit at a time, allowing you to mass-produce top-end units like thors and battlecruisers at the same rate as marines.
As for mercenaries, the Siege Breakers. When compared to regular siege tanks, they have 33% more hp and 66% more damage. This translates to doing 100 damage per shot unupgraded. The only other mercenaries that come close to this level of improvement are the War Pigs, who are still a very limited number of Marines. They even come at a gas discount along with the mineral penalty compared to simply building regular siege tanks.
The Hive Mind Emulator can turn the dreaded air-version of the final mission of the campaign into an easy breeze by building enough of the structure around your base in order to take control of every Mutalisk and Brood Lord that the enemy sends towards ya.
Brood Lords, period. They can spam broodlings while remaining outside of turret and goliath coverage. If you go into a mission where they're present, better amass a group of vikings as soon as you can- they're the only counter cheap enough to mass build on a short notice (and take out brood lords should the other player position the unit over terrains not reachable by land units).
The Scourges in the Lost Viking arcade game.
The Tal'darim to Raynor. In a couple of the artifact missions, the starting dialogue has the Tal'darim making flowery, over the top threats to Raynor, followed by Raynor being merely annoyed at having to fight them yet another time.
Goddamned Boss: No matter how many times you kill Maar, he will always come back (and each time stronger)
If you're having trouble deciding what to spend credits on in the Armory (because you're right—even if you get every research point and complete every mission in the game, you will not get enough credits to buy everything), then once you've gotten your protoss and zerg research maxed out, go redo any previous mission that gave you zerg or protoss research samples, and then check the research console in the lab. You'll gain extra monetary credit for the surplus samples you've collected so far, including the ones you've already cashed in. Fixed a few months after release as an Obvious Rule Patch, since the intent of limited credits was to force players to pick and choose on upgrades.
There's also one in "All In," the Nintendo Hard final mission. Every so often during the mission, Kerrigan will attack your base and is almost guaranteed to do terrible, terribledamage when she does. However, there is a glitch that sometimes occurs (still not sure how it's triggered) that results in her approaching the base halfway and then turning back. If this glitch is triggered she'll do this over and over again for the rest of the mission, thereby making it a lot easier. Other times (if the player chose to do the mission "Shatter the Sky" instead of "Belly of the Beast") Kerrigan will find herself trapped by two or more Nydus Worms and will remain trapped so long as the player refrains from using the artifact to sweep the board. The dark side is that which of the two paths to your base Kerrigan takes doesn't seem to be properly randomized.
In the protoss mini-campaign, it is possible for the endlessly-respawning hybrid (Maar) to attack once, then stand harmlessly outside the player's base doing nothing unless attacked. This frees the player to focus on freeing the prisoners in Maar's base without having to worry about protecting his/her own base—even on the highest difficulty level (glitch noted in January 2013).
In addition, it's possible to abuse Maar's teleport ability by getting him stuck behind world doodads if he jumps to a unit that is behind the doodad wall. Once he's trapped, he's forever stuck there unless you bring a unit close to Maar again.
In The Devil's Playground, there is a glitch with the brutalisk that gives the player twice as many research point than normal when the player kills it and doesn't already have any Zerg research points.
Harsher in Hindsight: Tosh at the end of "Breakout" dismisses the notion that overthrowing Mengsk would do any good stating there would be a "new Mengsk." His remark is likely closer even he imagined by the Nova Covert Ops when the Defenders of Man attempt to overthrow Valerian, and they use the same trick Mengsk did to bring down the Confederacy by using Psi-emitters to cause Zerg invasions.
Memetic Mutation: "Bros before hoes" and the reverse has been used to refer to siding with Tosh or Nova at the end of their mission chain. It also pops up due to the campaign ending where Raynor shoots Tychus to protect Kerrigan from him.
High Templar Karass; He has glowing orange eyes that no other protoss has, he has his own speech set even though he's never playable, his only role in the campaign is to lead a charge of Zealots through a Zerg barricade so that Zeratul can get the last piece of the Prophecy, and then pulls a Heroic Sacrifice by duelling with the Queen of Blades so that Zeratul can escape with the prophecy. He is seen in only one sixth of one mission in the campaign, but his actions may have saved the Universe.
Urun and Mohandar who make no other appearances in-game outside "In Utter Darkness." They are even absent when the Protoss campaign, Legacy of the Void, was finally released. Mohander at least appeared in a short story leading up to Legacy. His death there is the reason why Vorazun is on the Twilight Council.
Much of the campaign, especially the missions between the Mar Sara introduction and the Char finale, could be classified as this.
Hanson's and Tosh's storylines come off feeling like Filler arcs, and nothing about Matt's rebellion arc starting up the Korhal revolts makes any real impact in the later expansion games. All of these missions could be cut out, and nothing would feel out of place. Hanson's mission in particular take a long time to complete by default.
Unlike Char's choice mission that was connected to how the final battle would play out, the two choice missions for the Hanson and Tosh arcs existed only to to add a couple what-if scenarios that didn't leave much impact on the later expansions. They were, for the most part, pointless.
The Artifact search as a whole, which followed the same basic formula that rinse and repeated five times. 1) Go to a planet with an Artifact fragment. 2) Grab Artifact fragment from the enemy. 3) Leave planet with the Artifact fragment.
Paranoia Fuel: Between Duran, Raszagal, and that one short story about the zerg changelings, you'd be justified in going into the game suspecting everyone and anyone of being a sleeper agent for the Swarm. Just about the only people not worthy of freaking out over are Tychus because it's obvious who he's going to betray you to and Hanson. ...Oops.
"Maw of the Void," which is a map that offers very little replay value after beating it the first time around with mass Battlecruisers. It becomes quite clear soon after that there is nothing that can withstand the Rip-Field Generators to constitute being a worthy follow-up strategy; resulting in the same old stale experience every time this level comes around during a Wings of Liberty play-through.
The Prophecy missions. Sure, you get to play as Protoss for a bit, but the levels are incredibly long, there's a very limited roster of units you can build, and the music is austere and stale. The final level, "In Utter Darkness", is an extreme case, where the level lasts well over 30 minutes by default, and only ends when all of your units and structures are destroyed, which takes a long time.
Donny Vermilion may be a Dominion stooge (at least at first) but he presents a compelling argument when calling Raynor out for continuing his revolution during a massive Zerg invasion. Mengsk may be a brutal tyrant, but the Dominion military is the only Terran presence in the sector with the strength and leadership to oppose the Zerg; by constantly attacking their troops and inciting rebellion, Raynor is hindering their war effort against a genocidal foe.
"Aces High". All In the final mission is made much more bearable by the fact that every so often you can just use a superweapon to take out all the zerg either attacking your base, or on the way to attack your base. Except that to get this award you need to beat it while only using that item once....
The high-score achievements for the Lost Viking mini-game are this if the player is not familiar with its game genre.
"In Utter Darkness". You must kill a certain number of enemies to win, and have bonus objectives that require defending a key building for 25 minutes. Not too bad on Normal, but the Difficulty Spike is more noticeable in this mission on Hard and Brutal; not only are your enemies much stronger as you would expect, but the number of kills for the main objective increases, effectively making the mission last longer. The developers even seem somewhat aware of its difficulty: it's the only mission where all three Achievements for it can be earned playing on Normal difficulty, every other mission has an Achievement that can only be eared on Hard.
"All In" pits you against waves of Zerg on two choke points, you have to defend the MacGuffin for the entirety of the mission, and you have to deal with regular attacks by either swarms of mutalisks or nydus worms. By far the worst part though is the Goddamned Boss that attacks every few minutes, and uses a One-Hit Kill ability and a Herd-Hitting Attack as spells in addition to a powerful normal attack. You can put four bunkers, three siege tanks and perdition turrets at a choke, and the boss will still break down the door. Once you chase it off for a few minutes, you then have to rebuild your defenses because the normal Zerg are still coming.
Special mention goes to "Engine of Destruction" which really pushes your limits (especially on higher difficulty) as to how fast you can manage up your base-building to have a large enough army that can protect/repair the Odin during its rampage around the map.
Another honorable mention is the higher difficulties for "The Great Train Robbery", which offers the player very little time to build up a large enough army that can destroy each train that the Dominion sends out. It also doesn't help that resources are pretty limited on this map.
The higher difficulties for "Welcome to the Jungle" is said to cause some people a bit of trouble. One of the primary reasons being that the enemy Tal'darim faction will have a good portion of its entire Protoss tech-tree available to it despite the possibility of the player choosing to play this map quite early in the campaign. As a result, the player may end up with a major disadvantage having a shallow Terran tech-tree against almost the full-might of the Protoss. Another issue that makes this mission difficult for some people is the amount of stuff people have to pay attention to. At first, it's clearing out the map to reach the gas canister locations. Next, it's fighting through the map to reach the gas canister locations that the Tal'darim are trying to close off. Soon enough, it will be time to clear out the Tal'darim expansion so that the player can get their own second base. Oh wait, your base is now being attacked by the Tal'darim, but while that's going on, I need to protect the gas canisters I'm collecting since they're about to be hit by Tal'darim counterattacks trying to stop the gas from being stolen. Oh damn, I still need to grab the Protoss Research as well!
It's hinted at (and blatantly obvious early on) that Tychus is being threatened by Mengsk into eventually betraying Raynor. When he finally does, it occurs during the last cut scene of the game and the only thing it changes is that Tychus is now dead.
Finishing up Tosh's Covert missions heavily implies that his Spectre faction, as well as the people that Raynor's Raiders broke out of New Folsom, will aid in their battle in taking down Arcturus' Dominion. However, aside from Spectres becoming a buildable unit at the Barracks, the plotline never goes anywhere in the storytelling.
For Matt's Rebellion missions, there's never any after-effects for starting up the Korhal revolts after the "Media Blitz" mission. Even in Heart of the Swarm, when Kerrigan's newly developed Zerg Swarm assaults Korhal in the final arc, you wouldn't know that a civilian revolt had taken place there in the previous game.
The revolts arising from the expose in Media Blitz could have been put down with extreme prejudice by Arcturus, considering the fact that in Heart, even after Valerian's success at deinfesting the Queen of Blades, Arcturus still used his half of the military to crush Valerian's troops.
Kerrigan's Zerg Invasion that starts up on the last Mar Sara hold-out mission (Zero Hour) left a lot to be desired regarding how much it shaped the world-building as it was nothing more than a plot-device for the Queen of Blades to go around the Koprulu Sector searching for pieces of the Artifact. Once the invasion was done with, nothing had changed.
When the developers discussed content that was axed from the campaign, one of the possible story-lines included a "crew mutiny" plot where some of Raynor's crew members aboard the Hyperion turn on him due to being underpaid, and have had enough of working under harsh conditions. Some remnants of this storyline still exists in the officially released game, such as Tosh's Redstone mission being what would have provided the funds for Raynor's disgruntled crewmates, or Milo Kachinsky suddenly going off on a rant about Raynor selling them out to the Dominion so that he can team up with Valerian Mengsk. If the plot was implemented further, it would have been the perfect opportunity to provide some much needed character depth for those working under Raynor's Raiders, as well as explain why people would continue to follow Raynor when it's quite clear to the player that the war against the Dominion has taken a toll on him.
Portraits in conversations are advanced anough to look angry, sad, etc. However, they have an annoying tendency to "reset" to the default face for just a second after they finish their lines, leading to it looking like a bunch of robots simulating emotion.
The Untwist: Tychus betrays Raynor. The hints are so obvious you'd have to be blind to not see them, and they're so obvious you'd think they're red herrings. Considering the fact that Tosh has psychic powers, you can pretty much take what he says to be accurate.
Mengsk and Kerrigan get outsmarted a few too many times, given that the both of them were Magnificent Bastards in the original game. Even when the Raiders are operating directly on Korhal, on the outskirts of the Dominion capital, Mengsk and Warfield are entirely ineffective, and Kerrigan is equally inept even when the Raiders and Dominion are invading Char. The latter, though, is given a Hand Wave that most of the Zerg were away from Char at the time, but the rest of the campaign has no such justification for Kerrigan's incompetence.
Mengsk's case is probably justified in that years of ruling the Dominion have made him more complacent as well as the sense that he wanted Raynor alive in hopes that he would assemble the Xel'Naga artifact to deal with Kerrigan, while hoping he could control any damage Raynor caused in the meantime. Kerrigan goes full swing back to her old threat level in Heart of the Swarm.