This has been a growing trend in modern media. With watchers at home now having the capability to pause the action in high resolution, production designers, writers, directors, and even musicians are taking every opportunity to place these hidden Easter Eggs for fans (such as myself) to pour through and gush over (those were both fluid references, but they still feel like mixed-metaphors). These Easter Eggs can appear and disappear in the blink of an eye. Some of them are even written in different languages. A few are even audio clips or the combination of different characters' melodies from previous shows or movies.
The level of detail is astounding! Meanwhile, Disney's decision to release each episode separately (which is how television series used to be released) has spawned a new industry of people making articles or videos like the two that I watched today. Teams of people are now dedicated to combing through movies and shows frame by frame, looking for any possible reference that might be contained within.
Certainly, it is possible to enjoy these movies and shows without delving so deeply into them, but there is such an amazing level of extra detail hidden within them. It almost feels like trying to unpack a T.S. Eliot poem (which are known for their multiple allusions and hidden messages). This new layer of complexity and design is beyond anything I would have expected from a such an otherwise passive medium of art. I have to say that I quite enjoy it as these extra layers allow for more time examining and making connections with shows that I already liked.