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.
In-Universe, Frozen's "Let It Go" (or the copyright-safe rewritten version) is this to The Xavier School for Gifted Youngsters. Many years after attending, many heroines are singing it together, and sheepishly stop when Wolverine enters, only for him to join in as well.
"Funny Aneurysm" Moment: In The Amazing Spider-Man, Batman and Superman laugh at Spidey for his "But those are the best kind" line regarding breaking the promise he made to Captain Stacy to stay away from Gwen and continue dating her. This becomes inherently less funny when we see what happens to Gwen in the sequel as a consequence of this promise being broken...
Their "Fast & Furious 6" HISHE had everyone except The Rock and Vin Diesel die against the tank. Including Paul Walker's character.
The Age of Ultron trailer has Ultron terrifyingly quoting Disney films, prompting Black Widow to exclaim "You're ruining my childhood". Agent Carter revealed the Black Widow program used Disney films to teach the girls english, mixed with subliminal messages.
Iron Man tried to justify the murder of Obadiah Stane by reminding Superman and Batman that if you throw a criminal in jail, he'll just swear revenge on you and break out. This bit of Genre Blindness takes effect in Iron Man 2, when dealing with Whiplash.
The conversation Superman has with Iron Man about killing your villains is even funnier after Man of Steel came along.
And now, with the announcement that Jessie Eisenberg has joined the cast of the Batman / Superman movie, the response to that is "yeah, well I'm Lex Luthor!''.
Iron Man objected to Superman comparing Siri to JARVIS, but now JARVIS also has an iPhone app.
How Thor should have ended? At that point when he got his powers back, and he had to return to Asgard to fight against Loki... Thor looks back at his hot girlfriend, and decides to leave all behind to stay with her. Besides the other surprises and differences in context, Thor: The Dark World ends basically that way.
In the "thanks for watching" section", Clark is floating in the sea with the appearance of Aquaman, whispering, "Justice League..." at the end. Apparently, it's confirmed that Aquaman is indeed the one who helped Clark after the oil derrick scene and there will be a Justice League movie.
Ho Yay: The Super Cafe segments involving Superman and Batman. Indeed in the Amazing Spiderman 2 parody, a deranged Spider-Man extorts Superman to turn back time to bring Gwen to life by pointing a gun to Batman's head and threatening to kill him.
MS T3k Mantra: Though the primary purpose of the series is to point out Fridge Logic, it's not above ignoring certain facts about the parodied series and creating its own Fridge Logic for the sake of a joke.
Sequelitis: General opinion of The LEGO HISHE 2 is that, while still funny in its own right, it isn't nearly as funny or creative as the first The LEGO HISHE.
Uncanny Valley: Purposely done to baby Renessmee in Breaking Dawn Part 2, mocking the use of CGI in the actual movies.
Van Helsing Hate Crimes: The end of the "Zombie Song" video could be seen as it, with Chris and Jill mercilessly and thoughtlessly mowing down the singing zombies. That said, they do want to keep their brains.