These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Howard Stark actually getting screen time, a rare thing in any continuity. And then they decided not to do the typical Jerkass version of him some continuities did, and there was much rejoicing.
For some, the news that the film would be directed by Joe Johnston, director of the highly underrated WW 2-set superhero movie The Rocketeer.
Alan Silvestri's Captain America March just makes you wanna stand up and salute something. The full thing is finally heard over the credits while numerous wartime propaganda posters appear. Let's hear it for Captain America! (Too bad it wasn't included on the soundtrack album...)
The Staaaaar Span-gled MAAANNNN, WIIIITH A PLAAAAAAAAAN!!
— Her fandom usually focuses on her Badass/Action Girl status.
— Her hatedom focuses on her Jerkass tendencies which make her Unintentionally Unsympathetic, and her lack of plot-purpose.
Complete Monster: It's the Red Skull, people. Is anyone surprised?
Also, the Nazi spy who uses a kid as a human shield when trying to escape from Captain America and then throws him into the river when he's done with him.
Demonic Spiders: The Hydra mooks with the arm-mounted flamethrowers. Cap is forced to yield every time they appear, regardless of how much ass he was kicking prior.
Tommy Lee Jones as Colonel Philips is in full-on jerkass authority figure mode, and is funny as hell.
Also, Neal McDonough as Dum Dum Dugan is both visually and character-wise one of the most awesome characters in the film, and provides much badassery while being completely human.
Similarly, JJ Feild as Falsworth, who despite having such a small role, is pretty badass and classy.
Erskine's also pretty awesome in his own way.
The nameless kid that gets thrown into the drink, too.
He also wants to kill Hitler and take over everything he has. That's pretty cool in itself.
Gratuitous Norwegian: While the words and sentence structure are correct, Norwegian theatres burst out laughing at the way the actors in the Tønsberg church pronounced their lines.
Harsher in Hindsight: The movie opens with an attack on Norway. The very day the movie was released, Oslo was bombed in Real Life.
Harsher and/or Heartwarming In Hindsight: Captain America's co-creator, Joe Simon, died about five months after this movie's release, but its box office and critical successes likely helped re-assure him of Cap's lasting value before he passed away.
He's Just Hiding: Some fans speculate that Red Skull had actually been temporarily banished from the mortal plane than killed. The fact that the way he was disintegrated was similar to the Bifrost travel in the Thor movie supports it.
It's not just the Bifrost travel effect. Look closely at the ceiling when the Red Skull first grasps the Cosmic Cube in his bare hand. It temporarily warps to a star-filled view of the same interdimensional void that the Bifrost travels through.
It should be noted that its unlikely that he'll return to the regular plane of existence, assuming he survived, as Hugo Weaving stated that he's not likely to return to play the character in future films.
Bucky, in following with the comics. They never did find his body in the film, after all. In addition, in the scene where Captain America finds him, he is strapped onto a bed, implying that they may have done some sort of experiment on him or at least planned it.
"Some sort of experiment" + "no body" + "plunge into icy river" = "Yeah, there's no way movie Bucky's actually dead." Winter Soldier, here we come!
Add to this the fact that Bucky's actor signed a six-picture deal with Marvel Studios, and it's no longer a question of IF he's just hiding. He'll be back.
Hilarious in Hindsight: Considering how Hugo Weaving made the phrase "Mister Anderson" memetic, they had a golden opportunity for him to address Captain America derisively as "Mister Rogers". We can only assume they didn't because the scenes where Cap and Red Skull meet aren't the best times to slip so spectacularly hilarious.
Iron Woobie: Cap. You can tell he's sad about waking up after most people he knew were dead, but he won't let that get in his way.
Launcher of a Thousand Ships: The title character himself. He's shipped with Peggy, Howard, all of his Avengers "love interests," Bucky, every single one of the Howling Commandoes...Super-Soldier's a super-suitor.
Narm Charm: That stupid but oddly charming Hydra salute. Makes for a bit of Fridge Brilliance as the two fists represent the heads in the Hydra motto.
Nightmare Fuel: Locked in a metal coffin, screaming in agony...
Pet the Dog: The Red Skull giving Dr. Zola the keys to the Hydramobile. Subverted in that act from such a Complete Monster means he is at least in part making sure that his car will be delivered to him at the rendezvous.
The Problem with Licensed Games: Actually, it's not that bad! While rough around the edges, and saddled with a slow, uninteresting beginning, the Captain America: Super Soldier game clearly is more than just a meager cash-in like the Thor or Green Lantern games; it's got an imitation of the combat system from Batman: Arkham Asylum and a really huge castle full of HYDRA goons to explore. Of course, it's not quite as good as Arkham Asylum, but imitation is the sincerest form of flattery.
In fact, in the preview of the game, one of the designers even lampshaded this trope and explained that they planned to subvert it.
Trailers Always Lie: Played with. All the scenes in the trailers occur in the movie, but the context of several of them gives them a whole different meaning. In a good way, natch.
Trailers Always Spoil: The trailer touting the fact that it's the #1 movie in America not only partially spoils a character death, but the final scene in the movie. Not cool, editors. Not cool.
Uncanny Valley: In the early scenes, it's quite obvious that the Red Skull is wearing a Hugo Weaving mask over his mutated face. The effect can actually make him look far creepier than his true face ever could.
Visual Effects of Awesome: They make Chris Evans look like DJ Qualls. The effect was so good that Roger Ebert couldn't tell which body was Chris Evans' real one!
The make-up for the Red Skull is fairly impressive too, especially the Hugo Weaving mask he wears, which has semi-obvious neck flaps and red areas around the eyes which make it more realistic.
Never mind that, what about the fact that 90% of the film is in-camera effects?