There is arguably no part of a movie, any movie, that will be scrutinised by fans quite as much as the story. It's a basic expectation that the narrative will make sense, and while plot holes are the most obvious downfall in this regard, there is also logic.
While not strictly gaps in the plot of a story, holes in a character's logic can leave a question mark over an entire movie. It can more forgivable for a character to take leave of their common sense if the consequences are only minor, but it's a different story when one of these decisions informs the narrative of the entire movie.
Some of the entries on this list are genuinely exceptional movies, but there is a major flaw if you think about it. Even if it's a classic, it can be slightly infuriating if you as an audience can see how it could have been over in minutes if a character just thought logically for a moment.
Disney, Marvel, Harry Potter, and even movies by the great Steven Spielberg have all been guilty of this. With just one logical decision from one single character, these movies just wouldn't have had any stories to tell at all.
Towards the beginning of Frozen, the relationship between Elsa and Anna as children is explored. As the song says, they used to be best buddies, until there was an accident with the future Queen's powers and she hurt her younger sister.
After taking his children to magical trolls, King Agnarr decided to lock Elsa up for years to stop her from harming anyone else with her powers, keeping them hidden away. Given all the information however, this was absolutely the wrong thing to do, and indirectly led to the events of the entire movie.
From seeing Elsa playing with Anna as small children, it was clear that she already had immense control over her powers. The only reason Anna was hurt was because Elsa slipped over, not because she lost control. There was no need to react the way he did.
Grand Pabbie the troll also told them that fear was the enemy. So, why in the world did he shut her off from the world and tell her to conceal her powers. It was exactly this that created the fear that would be her enemy, and ultimately led to her losing control. Instead, had she spent that time using, understanding, and honing her abilities, not shut away like there was something wrong with her, there would have been no eternal winter for anyone. Anna even said herself it never would have happened if Elsa had just told her her secret.