For example, 君の名は。/your name.. There's a scene where a girl opens her hand to reveal something a boy wrote on it. With the official subs, it puts the whole thing on the bottom of the screen, and does it early. Zero emotional impact. With the fan subs, we see it spell out as she sees it. It's a pivotal moment in the film that is lost with the official subs, and you need this fan sub, even with the dub, to get the full effect of what the director intended, what the Japanese audience gets.