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.
Big Lipped Alligator Moment: Susan and Lucy partying with Bacchus while the boys rescue Caspian. It has no impact on the plot, the mythology crossover is never explained, and it's never mentioned again.
Die for Our Ship: The Susan/Caspian shippers, despite the fact that there's absolutely no mention of it in the books, they never see each other again, and Caspian marries Ramandu's daughter at the end of Voyage of the Dawn Treader. Curse you Andrew Adamson for including that kiss.
Strangled by the Red String: In the film (not the book), Caspian and Susan become a couple. For five minutes at the end of the movie because he rescued her once from some soldiers. Suddenly at the end the two are snogging in front of a crowd, only for their relationship to end five seconds later after Susan and her siblings return through the portal to England, meaning she and Caspian will never see each other again. Thus, there was no reason to include their romance in the first place because it was doomed to end anyway..
What an Idiot: The assault on the castle in Prince Caspian (which did not happen in the book) gave huge helpings of this to Peter. To be fair, everyone from Caspian to Lucy calls him out on it. Caspian also deserves a share of this one because it was his fault in the first place that they lost the element of surprise; he went into the castle with his own agenda and despite the obvious results of him changing the plan in the middle of a Stealth-Based Mission he shows no responsibility or remorse for his actions. To maintain order among the Narnian army, Peter has no choice but to let it go and share the blame.