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.
A huge piece of Fridge Logic arises from a Plot Hole in How Pacific Rim Should Have Ended, which is an odd case considering that this series is specifically devoted to pointing out Fridge Logic and Plot Holes. In this episode, it asks, "Since Gipsy's sword was effective against one Kaiju, why couldn't Gipsy just stand at the edge of the Breach and use its sword to decapitate Kaiju whenever one appeared?" The answer should be plainly obvious to anyone who has seen the film, which spends a ton of time demonstrating that Kaiju adapt and therefore any defensive strategy (i.e. Jaegers) is doomed to fail with time. Gipsy's sword is no exception; if they just relied on it, eventually the Kaiju would adapt and render it useless. Not to mention that the Breach is too wide for the sword to chop across, and two of the final Kaiju were already out before Gipsy could arrive there.
A lot of jokes in the Harry Potter video are this (ignoring that time travel in the Potterverse results in a Stable Time Loop, for instance). The eagles joke in The Lord of the Rings video counts as well, since there are so many reasons why that plan wouldn't work.
The first video has Gandalf trying to get Bilbo to throw the One Ring into Mount Doom, even though if he were really that close to the ring and its birthplace, he'd most likely kill Bilbo and take the ring for himself.
The video for Desolation of Smaug has Thorin ask the people of Laketown for a load of Black Arrows, which would make sense, except it was explicitly shown that there's only one Black Arrow in the place. It also ends with Legolas killing Smaug with the Black Arrow, which he fired with his bow, even though Balin stated that the arrow had to be fired from a Windlance. And even if it wasn't the case, the Black Arrow didn't look like it could be fired from a normal bow.
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...
Harsher in Hindsight: Their "Fast & Furious 6" HISHE had everyone except The Rock and Vin Diesel die against the tank. Including Paul Walker's character.
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.
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.