There was a manga comic series called "20th Century Boys" which was a conspiracy thriller mixed with 1970s Japanese nostalgia. One of the story's scenes involve

There was a manga comic series called "20th Century Boys" which was a conspiracy thriller mixed with 1970s Japanese nostalgia. One of the story's scenes involved the protagonists rummaging through a library looking for a particular book. When they find the book and open it, a scrap of paper from decades ago falls out, which happens to be the vital clue to move the plot forward. When you are reading the comic book, right as you come across the scene where the heroes open the book, when you turn to the next page the same scrap of paper seen in that scene falls out of the actual book you're holding. That sent chills down my spine when I first encountered it; pretty genius.