Near the beginning of the movie, there's a shot of Rafiki holding up Simba in the sunlight on Pride Rock before all of the animals in the kingdom:
Later, there's a contrasting shot of Pride Rock. Instead of day, it's night; instead of sunlight, the moon is in the background; and instead of the various animals of the kingdom, there are only hyenas:
Visually, this illustrates the difference between Mufasa's reign and Scar's reign. Near the end of the movie, after Simba has been restored as king, his heir is also held up by Rafiki. The specific shot composition doesn't match, but it is in the daylight and before the animals in the kingdom, so there's a contrast again, this time between Scar's reign and Simba's reign.
These contrasts also show visually what Mufasa tells Simba near the beginning of the movie: "Everything the light touches is our kingdom. A king's time as ruler rises and falls like the sun. One day, Simba, the sun will set on my time here and will rise with you as the new king." In between the sunlit reigns of Mufasa and Simba, there's the darkness of Scar's reign.
An-other contrast is in the color. At the beginning of the movie, during Mufasa's reign, the colors are vibrant, but during the worst point of Scar's reign, when there's no food or water, the landscape is almost devoid of color, mirroring this lifelessness:
After Simba is restored as the rightful king, there's a revival, and the proliferation of colors returns:
The colors illustrate this change from prosperity to desolation and then back to prosperity.
Both of these contrasts (the day/night shots of Pride Rock and the change in color) also demonstrate the cyclical theme of the movie ("the circle of life").
