In movies and TV shows and the like, there are often details that the writers work in that are hard to catch at first sight, but can be found if you happen to look for those details. For example, Character N always wears a necklace as it was a gift from his brother, however, but during the last few episodes (or minutes, or movies, etc.) he hasn't been wearing it because he got in a toxic fight with his brother and none of the other characters notice it until much later.
Is there a way to work something in that the average reader might not notice while reading through unless they were specifically looking for it?
