The film is about the Black Widow – not just Natasha Romanoff, but also Yelena, Melina and all the other agents serving under the Widow program set up.
It makes sense that HYDRA would be researching a chemical to suppress free will, given how that's basically their main goal.
It makes sense that a young Natasha had blue hair rather than her natural red hair, as she likely chose that color in order to fit the American trend of unnatural hair colors, which would allow her to blend in in Ohio. Also, she likely chose to dye her hair blue because it was the one thing she was allowed to have control over while working for the Red Room.
All of Natasha's hairstyles are symbolic. In the beginning, her hair is blue, showing how happy and at peace she was living with Alexei, Melina and Yelena in Ohio, despite being somewhat aware that it was all fake. Then she presumably let her red hair grow out and got rid of the dyed blue parts, symbolizing the trauma and the "red" in her ledger. Then, two weeks after destroying the Red Room, she dyes her hair completely blonde, as she has wiped out the "red".
S.H.I.E.L.D. was run by a black guy, wearing black, with a neatly-trimmed goatee, shaven head, and an eyepatch. Their best known base is in the clouds. Dreykov's Red Room is also an organization of spies, run by a white guy with normal hair, an unshaved face, glasses, and he even wears black. Their base is also flying and secret. Everyone there is mind-controlled in some way, while S.H.I.E.L.D. allows its agents more independence. Fury is so paranoid he sometimes doesn't even trust his own men - for good reason, as it happens - while Dreykov is arrogant and overconfident. And most importantly, S.H.I.E.L.D. is run for actually altruistic reasons, while Dreykov is completely selfish. In many ways, it's a Foil to S.H.I.E.L.D.
Melina using pigs as test subjects for mind control, as Fridge Horror as it is, is actually kind of ingenious. Pigs are very intelligent animals and can be easily trained like one could do with a dog. Opening a door wouldn't be too farfetched. So if she wanted to test mind control on something before people, pigs would be a fair choice.
HYDRA is bad enough with their infiltration and the Algorithm. Imagine they could also have chemical mind control too. Dreykov - or whoever ordered the mission - may have accidentally saved the world, or at least pushed Project Insight back a few decades.
Dreykov has been the puppet master behind Russia’s super-spy program for decades, specialising in running mind-controlled infiltrator/assassins designed to be utterly loyal to him and programmed to be incapable of attacking him. The suspicion has to be that Dreykov sniffed out HYDRA’s existence a loooong time ago and his overwhelming paranoia was a result of knowing who the real players were and what they were capable of.
It's no surprise that Dreykov falls for Natasha's interrogation gambit - living alone on a flying fortress to evade enemies while surrounded only by people chemically brainwashed to be unquestioningly loyal screams of a man who is relieved to finally be able to let his guard down after erecting all these barriers around himself. Which makes Dreykov quite a foil to Natasha, who does not excessively fortify her position when she goes into hiding but stays mobile and alert, even stating that she works better under stress. By the same token, it's not too difficult to peg Dreykov as somebody who will only too happily divulge his plans once there is somebody around who actually listens because they are interested in what he is saying, rather than listening because they have to - though Dreykov himself remains quite oblivious that he is, in fact, acting just like one more diva, as Tony Stark would have put it.
Alexei's stories about fighting Captain America are seemingly treated as him making up stories. But the revelations of The Falcon and the Winter Soldier about further super soldier experiments, it's possible Alexei wasn't lying and actually did fight another American super soldier fighting as Captain America. In fact, Steve Rogers slept through the entire Cold War.
During the events of Avengers: Endgame, Red Skull at Vormir gives Natasha the name of her father, "Ivan", which unsettles her as she has never heard of him. This film adds to this by giving Natasha her Internal Reveal that while her mother will forever remain unnamed, she is at least told what matters: that she loved Natasha enough to continue searching for her at the cost of her life. In the final years of Natasha's life, she gets some clarity (however incomplete) about her own family background, and subsequently played a big role in making things right by her adoptive families (Yelena, Melina and Alexei, as well as the Avengers and Bartons). It helps explain why she was at least satisfiedand ready for that Heroic Sacrifice in Vormir: she no longer has any loose ends in her life.
It's interesting to note that coming after The Falcon and the Winter Soldier, we get another show about two other people copying Captain America, Red Guardian and Taskmaster, for very different reasons - Alexei was Just Following Orders and ends up doing his own thing here, now that the obligation to be a propaganda icon has passed, while Taskmaster merely scanned his movements and can never replicate what makes Captain America, as evidenced by how her shield never rebounds back to her.
Her equipment and her move set show that she is a mere knockoff of the people she copies. She is not able to replicate Steve because her shield is not only not made of the right material, but is also smaller. Because her shield isn't the right material, it doesn't rebound back to her. This is shown in The Falcon and the Winter Soldier, where John Walker's scrap metal shield doesn't rebound well when he throws it and Karli Morgenthau kicks it away. Furthermore, because she is much shorter and less muscular than the super soldier Steve, she can't replicate his physical prowess as well. This is why she is also unable to replicate Bucky properly either. Because she is lighter than Bucky, a more muscular and lighter super soldier, she gets easily disarmed by a forearm block by Alexei, a heavier and bigger, and as such, physically stronger super soldier. For her knife, her knife is not even the right type. Bucky’s knife from his right holster is double edged, while hers is single edged, which will reduce her rate of attack. She is not able to replicate Clint simply because she is not left handed, and as such, has to wield her bow with her left hand instead of her right, like Clint. She probably doesn’t try to replicate T’Challa because she doesn’t have a Vibranium suit or claws, and as such doesn’t have the benefit of very sharp claws or complete protection from bladed weapons and guns. The hero she can perfectly replicate is Natasha. This makes sense, because not only did she most likely receive Red Room training, she gets to scan Natasha up close and personal instead of viewing video footage, which could likely be slowed down because of the camera’s framerate.
Taskmaster doesn't really perfectly replicate Natasha, either, but it's because the character was designed to replicate all of the various Avengers in combat style alone. Natasha is never just fighting, though. She is adaptable and pragmatic, goal-oriented and creative about it, even more so than the other Avengers. This is most apparent in their first battle. While Taskmaster is simply copying and one-upping her signature moves, Natasha is quickly evaluating and re-evaluating the situation and making use of changes in her environment. Taskmaster won the physical fight and captured the case, but Natasha knew that the real winner was the one who left the field with its contents. Natasha isn't hard (on the superhero level) to defeat in a straight-up fight. Her greatest asset is her mind, and Taskmaster simply cannot duplicate that, because Taskmaster has to be brainwashed into following the already-provided mission directives.
"American Pie" features the line "Can music save your mortal soul?" For Alexei, in a way, it does - singing it with Yelena is the first moment where he genuinely seems to be moving past his ego and becoming a better person.
The song also mourns a bygone era of America that symbolically ended with the death of Buddy Holly, an idea which speaks to Yelena and Alexei's character arcs—the song's celebration of the past parallels how Yelena holds on to the glimpse of American life that she enjoyed in Ohio, while Alexei has become similarly nostalgic for his past as a Soviet hero by the time he reunites with Natasha and Yelena. All the characters in the movie grapple with this idea of nostalgia, as well as its darker variation in the form of the Red Room's legacy.
Also "This will be the day that I die" - the first time we hear Yelena sing it is the day that her "fake" American persona and family (and childhood innocence) died. And ironically, the second time we hear her sing it leads to her reconciling with her past and creating a new life.
You don't hear this lyric during the actual scene, but at one point, the words "No angel born in hell, could break that Satan's spell" are sung. This foreshadows the climax of the movie. Natasha, Yelena, Melina and the other Black Widows are the "angels born in hell (The Red Room is hell)" At first, Natasha is unable to break "that Satan's (Dreykov) spell", the spell being the pheromonal lock.
At first, it seems odd that a quartet of Russian operatives are speaking to each other in English, but this is the language they all used with each other when they were last together.
It may seem strange that Taskmaster would so readily accept Natasha since she tried to kill her when she was only a child - but Natasha's actions only disfigured her. It was her father's decision to turn her into a brainwashed killer with no control over her actions, when it's entirely possible she could have recovered and lived a mostly normal life if he had chose to let her. She's also been forced to witness the horrible things her father has done to turn children into trained weapons, and probably understands why someone would have gone so far as to attack them both if it meant saving other girls from this fate.
Dreykov designed Taskmaster to copy several heroes even though, as stated earlier, she won't be able to efficiently mimic them. Taskmaster is a copycat because Dreykov is one. He's copying from more powerful people to look more powerful but also doesn't do as good of a job. He stole the technology and science for perfect mind control from HYDRA. His base can be seen as a copy of SHIELD's helicarriers and his plan can be seen as a knockoff of Project Insight, especially because it doesn't take as much effort as Captain America and his team needed to stop Project Insight.
Taskmaster is introduced watching footage of the airport battle in Civil War, and a good chunk of Taskmaster's move set is derived from the participants of that fight, not limited to Captain America, the Winter Soldier, Black Panther, Hawkeye, and Spider-Man.
It’s a good thing that the events of the movie happen because if Natasha didn’t reconcile with her first surrogate family and regain her faith in family, there’s a chance she would not have helped bail out the incarcerated Avengers because it’s implied that Natasha had no intention of doing so in the beginning of the movie, especially because of her spurning her friendship with Mason and saying she works better alone.
The parallels between Taskmaster and the Winter Soldier are rather obvious and so are the parallels between Dreykov and Alexander Pierce, leaders of organizations long thought dead but have been hiding in the shadows and have a surprising amount of influence and have a dangerous murderous brainwashed master assassin in addition to their other assassins which as MCU material such as Agents of S.H.I.E.L.D. revealed several loyal SHIELD agents were brainwashed by HYDRA.
The film subtly gives an answer to Yelena’s belief that the only difference between her and Natasha as Black Widows is that Natasha is worshipped as a hero, thus stating that Natasha is only a hero because of her skill set. Natasha isn’t a hero just because of her skill set. She’s a hero because she has the heart of one. This is shown by how she gets to the Red Room. Natasha appeals to the better nature of Melina and convinces her to make a path for Natasha and to help her in dismantling the Red Room.
Natasha watching Moonraker near the start helps foreshadow part of the climax, in that movie there is a floating station that the protagonists have to get into, which foreshadows that that what the Red Room is and what the heroes have to do as well.
In Russia, Christmas was phased out during the Soviet era and only became an official holiday again in 1991. Even if Melina and Alexei had lived ordinary family lives as normal children, they probably wouldn't have grown up celebrating Christmas. It's also observed on January 6-7 instead of December 25,note In some countries, especially European ones, celebrate the Three Wise Kings tradition instead of Christmas, which is celebrate in January 6. The gifts also come from the biblical Three Wise Men, instead of Sandy Claus. and tends to be celebrated very differently than in the west (primarily with festive family meals instead of gift-giving and decorations, which are features of New Year's Day celebrations instead). Melina and Alexei may not have even thought that the girls would care about Christmas.
Yelena is shown with strawberry-blonde hair as a child, which is probably why she was chosen to be part of the Ohio mission: she could pass for the redheaded Natasha's sister.
Fridge Horror
The stinger showcases Yelena being recruited to hunt down Hawkeye and kill him for his part in Natasha's death. This does not bode well for Hawkeye's family. Although his solo show shows that Clint himself was the only endangered one (and still, there are criminals with tabs on his family!), and who knows if he'd survive if not for Kate Bishop?
Judging by Dreykov's dialogue, the number of Black Widows could well be in hundreds or thousands, taking into account, according to Yelena, only 1 out of 20 survives the training, so who knows how many thousands of girls died because of Dreykov and how many more he planned to kill to achieve his purposes.
The mind control is terrifying when you think of the other purposes it was likely used for, especially by someone like Dreykov.
Could potentially be another reason for the forced radical hysterectomies...
Think about how many Widows just got deprogrammed. No past, nothing in their heads but a lot of bad memories and the skillsets to be some of the most dangerous spies/assassins on the planet. What's to say they all go straight? Even one or two could cause some major damage if they go into business for themselves... (And indeed, Hawkeye reveals a Widow turned hitwoman who became rich in the murder business)
This movie took place only a few weeks before Infinity War. We have no idea if Yelena, Alexei or Melina survived the Snap; or what kind of affect it had on their mission to free all the brainwashed Widows. It's probable that half of those still brainwashed got snapped and have just now returned, still under mind control...
This movie takes place roughly after Natasha goes on the run during Civil War and before Steve breaks the other Avengers out while Infinity War takes place two years later. Hopefully Yelena, Alexei and Melina found and freed most of the brainwashed Widows before that.
Hawkeye reveals that Yelena saved many Widows before she was snapped and that she wasn't the only Widow doing that. But whether there are enough on the loose, specially with the reveal that some are not brainwashed, but still dangerous as contract killers...
