People did that with Gravity Falls, granted, that show actually had ARG type stuff going on and whatnot, but still, anything ever that has a lot going on in the backgrounds, people begin to catch on and try to keep an eye out for things
And once they find those things and the creators continue that trend, people will begin to pay even closer attention to background things and document them online as soon as possible
...Just like everyone began pointing out every single animation error in My Little Pony...
But yes, they basically do just replay the episodes over and over looking for various details
