For example, search for [the matrix] and actors and related movies of movie up below the knowledge graph details. When you hover over some of those records, Google will show you the relationship between the two. For example, I hovered over "The Animatrix" and it says, "The Matrix and The Animatrix are part of the same movie series."
Here is a screen shot:
Google says this is a great and legit way to expand their bacon number easter egg in a more practical way.
Google says they are just starting out with this and you may see it for "major co-starring roles between actors, movies, and TV shows as well as highlighting family connections amongst famous people in the Knowledge Graph."
Forum discussion at WebmasterWorld.