There are some things that are too obvious to see: things we don't notice because they have been made part of the very atmosphere around us. One such thing is the modern attitude of segregating the generations.
What I mean is this: at almost all times in history, there were many parts of the world in which a child grew up interacting regularly with persons of all ages--as when, for instance, the child might work together closely with a live-in grandparent at some domestic task. But in the industrialized world of the 20th century, it became the new norm for children to be rigidly divided into narrow age groups. Thus one's crowd of peers became the social alpha and omega, the supreme authority in life. This produced what Jesus called "the blind leading the blind," as it became _uncool_ to respect the wisdom of one's elders.
Mr. Lewis, in writing "Prince Caspian," was boldly swimming _against_ this tide, by writing a tale in which the hero would be sunk like a rock in a pond if he _didn't_ pay heed to his elders--Cornelius AND Peter. The Peter Mr. Lewis actually wrote about was NOT so controlled by adolescent emotions as to have gotten himself into an unequal fight over a trifle at a train station; but the movie writers made that change, because they were _intentionally_ working head-on _against_ the clear theme of the whole book. They didn't want Peter to be the effectively-adult mentor for Caspian that Mr. Lewis wanted him to be--because that wouldn't fit with peer-group philosophy. Instead, the movie Peter had to be made a PEER of Caspian's, getting into a school-locker-room rivalry with him, and being pointedly made to look all wrong for _trying_ to be that mentor and leader.
Most modern teenagers attending the Caspian movie won't be able to see the damage done to the original story, because the creed "My peer group is all!" has long since become the very air they unquestioningly breathe. But they still _would_ have been able to appreciate the book's vision of Peter teaching and helping Caspian, if Walden had bothered to SHOW the book's vision of Peter teaching and helping Caspian. Young people are still smart enough to be taught--if only someone WILL teach them, instead of just stroking their self-esteem with "Teenager knows best" messages.