Look closely at the propaganda film that features Steve. As he holds up his shield to block incoming bullets, you'll see actual bullets bouncing off. Early special effects technology had yet to perfect the hidden squib so to get bullet shots on film, sharpshooters were hired to fire real bullets with reduced powder loads.
When Armin Zola, the scientist, visits Johann Schmidt, the Red Skull, you never see Johann's face. An artist is painting a portrait of him, and his palette consists mostly of chunky, deep red paint. The artist also looks visibly disturbed. Makes sense about halfway through the movie, when Johann takes of his mask.
In Thor, we are told that magic is more or less sufficiently advanced technology. The arc reactor (60s tech) and Tony Stark's miniaturised version (2010s tech) are inspired by the Cosmic Cube but built from first principles, rather than containing elements of it. They are current humanity's early approaches to technology of a level enjoyed by Asgard.
The Red Skull doesn't seem the type to take prisoners. This is probably why the army didn't want to mount a rescue mission - they didn't know that Skull was using the captured soldiers as labor instead of just killing most of them right away.
Dr. Erskine says that, "The serum amplifies everything that is inside, so good becomes great; bad becomes worse." Once put into Steve Rogers, it made Captain America. Put into Johann Schmidt, it made Red Skull. 60 years later, a reverse-engineered version was put into Emil Blonsky... and made the Abomination.
Plus the gamma radiated Hulk blood. Bronsky is a fierce mercenary soldier using a reproduction of the Super Soldier Serum. It's incomplete, but did seem to enhance what he was, a fighter/soldier. It gave him seriously advanced healing, agility, speed, and seemed to be adjusting his bones slowly to handle receiving a curb stomp battle. We have to also look at the series of events. Steve Rogers received a full vial of serum into each major muscle and enough vita rays to shut down the power grid, all at the same time. Bronsky received a syringe of "we hope it works" serum, broke every bone in his body, recovered, then received some gamma blood. This ties into the old plot device regarding the gamma radiation where the person's subconscious influenced the outcome. The fact that they were able to tie this in with the Red Skull is pretty ingenious.
Also, it acts as a good justification for the Disposable Superhero Maker: They probably replicated Erskine's formula a long time ago, but as it's controlled by General Rippers like Ross instead of Cool Old Guys like Erskine, they only used it on jerks like Blonsky. That means all they've ever produced are Abominations. To get a super soldier the likes of Captain America, The Government would have to use the serum on a Good Man... and if they ever did, they haven't let him walk around.
On the train just before Bucky falls out of the train he picks up the captain's shield to protect himself. It seems straightforward enough but when you think about what happens in the comics it gains a whole other level of brilliance. In the comics, Bucky takes over being Captain America for a while after Steve is thought dead.
When Red Skull becomes angry at Steve Rogers' "I'm just a kid from Brooklyn" answer to what makes him so "special" becomes even more obvious when you consider that he was exiled from Hitler's elite circle for not resembling the Aryan ideal anymore. Meanwhile, the Blond, Blue-Eyed Steve Rogers has essentially become the ultimate Aryan. Steve is essentially everything Red Skull wanted to be, and he's on the Allied side. More than that, when Steve Rogers denies there is anything special about him, he implicitly denies there was anything special about Schmidt. That is what really angers the guy.
The original idea, when the movie was first announced, was for half to be a WWII period piece and half to take place in the present day. So why didn't they do that? Because Thor already gave us a fish-out-of-water story. (Though the lack of a solid civilian cast for Cap post-WWII might have also had something to do with it.)
Schmidt and Zola were able to use the Tesseract to turn Hydra into an N.G.O. Superpower. Howard Stark salvaged the cube but doesn't do the same? Ohhhh yeahhhh... Because he's not a megalomaniac! The Tesseract could be used to build powerful weapons, and would make building an empire simple via Phlebotinum Dependence - any attempts to turn the technology against them would be futile as the Tesseract is the only way to power it. But powering the world was something else entirely. The Arc Reactor technology he struggled with to his dying day was his attempt to make the technology widespread - turn nuclear warheads into nuclear reactors.
It also shows Howard's reasoning in deporting Vanko - Hydra proved that the technology was easily weaponized, but Stark refused to follow in their footsteps and was deeply disgusted by Vanko's attempt to plunge the world into Hydra-style Tesseract-powered warfare. Tony was less successful in protecting the technology from Senator Sterns and Hammer - the assholes only saw Arc Reactor tech as a weapon, never understanding how much havoc Hydra wreaked with it - until Vanko cut loose.
It also goes a way towards explaining some of Tony's extreme 'my technology, you no touch' reactions to the arc reactor and the suit, if he had it drilled into his head from early on that anything falling into the realm of 'tesseract stuff' had to be strictly controlled and kept out of government hands.
Iron Man 2 has the Stark Expo song Make Way For Tomorrow Today which is a Disneyland Tomorrowland type song in the vein of Great Big Beautiful Tomorrow. This isn't coincidence - MWFTT is written by one of the Sherman Brothers, who were legendary songwriters for Disney, including that Tomorrowland song. You might also think it isn't a coincidence that Howard Stark appears to be a mix of Howard Hughes and Walt Disney (Hughes for the tech, Disney for the family friendly showmanship and public persona).
Steve doesn't know what fondue is because it wasn't popular until the 50s and 60s. Howard Stark of course knows what it is because he's rich and indulges in all sorts of high brow tastes that the common masses don't know.
Also doubles as Fridge Horror, but Bucky was repeating his serial number over and over just before Steve rescues him. A quick Google search provided an answer: a soldier is only supposed to give their name, rank, and serial number when being tortured for information. HYDRA must have been torturing Bucky. Or brainwashing him. Though it's probably Translation Convention, this may instead have implications of Switch to English for HYDRA's higher-ups speaking in English instead of German if some of the mooks are actually brainwashed Allied soldiers.
Remember how in Iron Man 2, the shield Tony uses to prop up his particle accelerator is mostly made of plastic with a little bit of metal? Howard Stark says that the Vibranium shield is made out of just about all the vibranium they have; the plastic shield Tony's got is just a stand-in for the real deal.
Why did the spy wait until after the experiment? He had to make sure it worked. If it failed, he just would have sent back a message saying the Allies are still no closer to a proper serum. But since it worked he followed his directions carefully; notice that the only time he actually stands to confront Steve is when he has the child hostage, any other time the spy's either trying to lose him or taking potshots to keep him in cover while extending his lead.
Steve grabs a helmet that belongs to one of the dancing girls when he's going off to save Bucky. Just a way to justify his trademark blue helmet with the white A, right? Well...earlier in the movie, we saw how well normal army helmets fit the man. The serum didn't expand his skull: he needs a helmet fitted for someone smaller than the average soldier.
The "Heil HYDRA" salute looks like a doubling up of the Nazi salute, which is sort of cheesy...but their motto is "Cut off one head and two more will take its place." Something doubled-up makes perfect sense.
Having the black dude be the one to capture Arnim Zola wasn't just an attempt at giving him one scene of focus - it was twisting the knife in the wound. Nazi or Hydra, they're Aryans after all.
Take a close look at just where Schmidt picks up the Cosmic Cube: Tønsberg. Which Thor established was the site of a major battle in the Asgardian/Frost Giant War. The few surviving humans would have had first-hand experience just how dangerous the powers Asgardians and their like are dealing in can be to humans, and a great reason to feel indebted to the Asgardians. In other words, the perfect start for an Ancient Tradition guarding a (seemingly, at least) Asgardian relic.
The super soldier serum may have made Steve stronger and faster, but he remained Adorkable, with little charisma to speak of. The stage shows he starred in took care of that; he went from needing cue cards taped to the back of his shield, to the charismatic hero figure he was destined to be.
Bucky's body is never shown, he falls into icy terrain, and just like with Steve, he's found by Sovietic soldiers still in the ice and is used to become The Winter Soldier.
Prior to the procedure, Erskine has to point out to Peggy that she should be in the observation booth. It's subtle, but an indication that she's already falling for him.
Not to mention that during the procedure when Steve starts screaming in pain, Peggy is the first person to shout for them to shut it off.
Plus, there's also during the "Grenade!" scene where Peggy is actually the only person running to Steve diving heroically over the grenade, while everyone else ran for cover.
He may have been a scrawny guy having trouble with the basic training run, but Peggy was clearly amused he solved the flag problem.
Prof. Erskine just happens to be there when Steve talks to Bucky passionately about joining the fight. Kismet? No, he's there at the invitation of Howard Stark, who was presenting at the expo, and nipped over to the recruitment tent because he's always looking for recruits.
Steve's sharp memory could be a result of the super-soldier serum.... Or then it might be due to artists often having excellent memory and eye for detail. He may have been asked to emulate another artist's style or reproduce a small picture on a larger scale.
Perhaps a small, unintended bit of brilliance. When the Red Skull gets taken into the Bifrost, the effects almost make it look like he is getting burned. In addition, he gets taken away, rather than dying like the rest of HYDRA. In Greek mythology, the only way to keep a hydra's head from regrowing is to burn the stump after cutting the head off. Also, the last head of the hydra is immortal, and most myths state that it is pinned under a boulder to deal with that. Maybe not the exact same thing as transporting it to a different realm, but kind of an interesting connection.
A Case of Fridge Horror: Wonder why all of the prisoners in Hydra's work camp are Americans, with a few British and French thrown in, instead of the Polish or Russian soldiers they would've captured first? Consider that Hydra clearly doesn't care about it's slave labor's safety: they just ran out of everyone else. Or like discussed above they might have been brainwashed and added into HYDRA ranks. Remember we never actually see any of their faces.
Rogers rejects the team Phillips wants to assemble in favor of asking the POWs he rescued to return to the front. Not only did he see them in action and approve of their tenacity, but he would have compared them subconsciously to the men he was at the Project with. There was a way besides Cutting the Knot to get that flag off the flagpole - they could have helped each other. Brawny guys like Dugan on the bottom. Mid-sized guys further up, bracing themselves against the flagpole. Rogers, the "ninety-pound asthmatic" determinedly crawling up the pile to retrieve the flag. "Whoever brings me that flag gets a free ride back to base!" No reason it couldn't have been everyone presenting him with the flag, and refusing to abandon the others. Instead they were yanking each other off the flagpole like crabs in an open bucket.THAT is why he wanted those weirdos - they worked together almost instinctively despite not only being from different units, but different countries.
Why is Bucky alone in no wearing any special Stark-designed battledress, opting instead for a peacoat, aside from paying homage to the comics? It is because since Brubaker's overhaul of the character, Bucky is the Invaders' point man and scout. He was possibly required often to scout ahead, dressed civilian-ish, to gather intel.
The way Cap's Mighty Shield kept on getting its paint job messed up is odd for a supposedly indestructible shield, but read this review. The shield is itself indestructible, but the paint is just paint - it must be maintained and cared for to show the shield's true glory. So it is with America itself - we are not unsullied and invincible, we screw up and falter and make too many excuses, there is work to be done for us to shine at our best, but underneath the scarring the American Dream is unbowed and unbreakable. The star at the center also doesn't seem to get scratched up, perhaps representing the ideals that's at the heart of every American's desire to live up to that American Dream.
Schmidt mentioned early on that he'd been sent to the Swiss Hydra base because he "no longer fits Hitler's Aryan vision". Which could mean either his Red Skull deformity or him being dark-haired (even before procedure if the Erskine flashback is any indication). Take a look at the few Hydra employees we've seen unmasked, like the agent who shot Erskine or Mr "We fought to the last man". All dark-haired. This subtly hints that Hydra is basically a Reassigned to Antarctica for the Nazis - adding to Schmidt's entire motive of putting down the Reich, so to speak.
"Hey, wait a minute, if Schmidt had all of those targets in Europe, why was he taking the Valkyrie to New York first?" "He probably wants the ground troops to take care of them."
Either Zola was lying about being a vegetarian because he was paranoid about the steak, or he really was a vegetarian. Like Hitler.
Part of the reason why Steve is so immediately disoriented and afraid when he first wakes up in 2011: the SHIELD agents are wearing heavy black armor, not too immediately dissimilar from HYDRA armor, and the technology he encounters as soon as he breaks out is highly advanced beyond what he's familiar with, beyond, again, HYDRA technology. Even if he doesn't think they're HYDRA, he's going to be drawing some automatic and very emotional connections to HYDRA regardless.
The name "Vita-Rays" is a bit dumb-sounding and vague until you realize that this was probably the point. Erskine was trying to keep the supersoldier creation process known only to himself, so it makes sense that he'd hide not only the formula but the name of the radiation involved as well. This is typical operating procedure for some secret government projects. The use of "tank" to mean a tracked armored vehicle with at least one powerful gun came about because the British were attempting to fool the German Empire into thinking it was a mobile water tank. It's good for keeping eyes away from your project by hoping your enemies think it's just something boring they can easily take care of later, or, in the case of the Vita-Rays, not fully sure what it is and maybe it is just a distraction because it's got a stupid name.
The first we see of the HYDRA soldiers, they're dressed and armed no differently like other Nazi soldiers. Once they have possession of the Tesseract, we gradually see the HYDRA soldiers look less and less like regular Nazi personnel, with their uniforms getting more heavily protected and their tech obviously getting more advanced. Then when you consider that Red Skull probably had HYDRA completely split off from the Nazis upon making the discovery in Norway...
First, Steve gets 4F as a grade. Then, he gets 1A. They might be actual military grades, but think about it: a guy played by Chris Evans went from 4F to 1A.
A very minor point but it does make an interesting parallel between the Captain and Red Skull. When Zola is trying to transfer the Tesseract's energy to an artificial cell, he stops at 70%, afraid to go further since it's untested technology, but Skull pushes it to 100, unwilling to stop going all the way after waiting so long. Later when Steve is undergoing the serum infusion, as Stark pushes the energy to 70% Steve begins to scream, and as Erskine tries to shut it down, Steve refuses to let him, insisting he can do it, and they keep going.
A bit of both Brilliance and Fridge Horror: Jim Morita's bitterness is justified when you consider that his family back home is likely in an internment camp.
Cap and company fighting HYDRA rather than straight up Nazis. It might have come off as disrespectful to the real heroes of World War II to have Captain America winning fights against a very real enemy. Adding an element of a secret front to the war subverts the Reed Richards Is Useless problem and establishes him as a folk hero, someone who was there, but mysterious because dealing with this secret underbelly of super science.
Hats off to the scene with Erskine saying "The first country the Nazis attacked was their own." This may have been a wide appeal summer blockbuster/ two hour ad for the Avengers, so bonus points for going out of their way to lend some shades of dimension to a real life historical tragedy.
A sign behind Cap in modern-day Times Square says "Innovating for the 21st century." Indeed.
As of Thor: The Dark World, we know that the Tesseract is one of the Infinity Stones; more specificallynote according to Word of God as of March 2014, but supported by instances from this film and The Avengers, it's the Space Stone. So what specifically did it do to people shot by those weapons?
Colonel Phillips originally favored someone like Hodge to be selected for the Super Soldier experiment. Dr. Erskine said Hodge was a bully (not without reason). If Hodge had been selected, the world might have ended up being the setting for Red Skull vs. Red Skull.