One of the curious issues with sequels is that the people who make them don't always seem to remember - or acknowledge - the details from the original films. This has created some frustrating cases in which characters essentially forget they can do things over the course of a franchise. You don't always recognize this at the time. It's something that generally becomes apparent with second or third viewings. But once you identify one of these inconsistencies, you can never unsee it.
Sometimes a cinematic superhero forgets one of the special powers that previously gave them an important leg up during a fight. Other times, a character is depicted as having a distinct skill that's strangely ignored when another situation arises in which it might be useful. Not all of these are unforgivable. In the mildest cases, they're more amusing than anything. The most blatant examples, though, completely change how you think about the protagonists. After all, a character who forgets about their powers just comes off looking foolish.
Vote up the sequels that most egregiously ignore their predecessors.
The most surprising moment in Transformers: Revenge of the Fallen comes when Alice (Isabel Lucas) tries to seduce Sam (Shia LaBeouf), only to be caught by his girlfriend Mikaela (Megan Fox). During the scene, Alice reveals herself to be a Decepticon in disguise. She looks human, but she's got a mechanical tail and tongue. It shows that the evil Transformers are capable of turning into more than cars and soda machines - they can transform into actual people.
That's a game-changing revelation, yet one that is never repeated in any of the subsequent Transformers pictures. If the Decepticons really want to carry out their nefarious schemes, infiltrating society by disguising themselves as human beings would seem to be a great way of doing it. Instead, they weirdly ignore this advantage.
All the Marvel superheroes have fascinating powers of one kind or another. The "illusion" power belonging to Scarlet Witch is one of the coolest. She demonstrates it during her introduction in Age of Ultron by showing each of the Avengers their own worst fear. The effect proves deeply rattling for the superheroes.
With a power that devastating, it's beyond weird that, in subsequent MCU installments, Scarlet Witch seemingly forgets she even has this ability. Even in Infinity War, when Thanos has all the Infinity Stones and is getting ready to wipe out half the world's population, she never thinks to use it. Nothing makes a person crumble like pure pants-wetting fear, so why not unleash the illusion power on the big purple guy? It's even more useful than the telekinesis she typically relies on.
Ghostbusters II opens with the words "FIVE YEARS LATER," and it's astonishing how much the city of New York has forgotten in that time. When we meet back up with Peter Venkman and his cohorts, they're out of business, having been sued for property damage incurred in their line of work. After getting back into the game, they're hauled in and tried in court. The presiding judge calls them "charlatans" and sentences them to 18 months in jail at Rikers Island. Later in the movie, the mayor's assistant has them committed to a psychiatric hospital.
Apparently, no one in New York remembers how the Ghostbusters took down that gigantic marshmallow man that tried to wipe out the Big Apple. In fact, it's almost like everyone has forgotten that these guys saved not only the city, but probably the entire world. This convenient neglect of their accomplishments in the original film seems designed to make the characters prove their worth once again, even though logically it's already been proven beyond a doubt.
There's a scene in the first X-Men movie in which Mystique disguises herself as Storm in an effort to fool Wolverine. As she walks into the room, he begins sniffing. They converse, and then he suddenly whips out his claws and plunges them into her midsection. The sniffing suddenly makes sense. He could smell that it was Mystique!
Flash forward to X2: X-Men United. This time, Mystique disguises herself as Jean Grey and attempts to seduce Wolverine. He falls for it, until he feels the scar on her back. Seemingly, Wolverine forgot he has the ability to detect her scent. Presumably, she doesn't smell any different, so his failure to identify her the same way twice seems inconsistent.