That transition from heroic to devastation when Simba returns to Pride Rock is heartbreaking.
Everyone always talks about Mufasa's death (understandably), but one scene that really gets to me is the transition when returning to the pride lands.
Simba running heroicly through the desert back to Pride Rock, but the music and transition turning gloomy and heartbreaking as Simba steps back into the Pride Lands. And his horror as he sees the devastation Scar has caused. Fantastic moment that always makes me tear up.