What exactly is a shared universe in film? It’s basically when unrelated movies share certain characters and exist within the same world. It combines two or more standalone films, sometimes from different writers/filmmakers. We see the concept of a shared universe in many forms of media: movies, comic books, television, and literature. All the films below could exist in the same universe. Don't believe it? There's plenty of evidence!
It’s important to note the idea of a shared universe can just act as a very small part of a film. It may be just a winking cameo, like when Dr. Raymond Stantz (Dan Aykroyd) from Ghostbusters, drops in for a quick scene in Casper.
Other times, the concept of a same universe theory is the groundwork for an entire network of movies. You've likely heard of the Marvel Cinematic Universe, combining the forces of many different superheroes. But there are also a few post-modern directors that elicit rabid same universe fan theory. The same universe theory allows us to loosely link all of Quentin Tarantino’s movies, his canon of work is called Tarantino Universe. Sometimes his characters are related, sometimes they work together, and sometimes they just go to the movies together. Some of the Tarantino connections are stronger than others, and the ones listed below are totally cut and dry.
'Casper' and 'Ghostbusters'
Kevin Smith's View Askewniverse
'Pulp Fiction' and 'Reservoir Dogs'
'Machete' and 'Spy Kids'
Universal Monsters Cinematic Universe
'Coming to America' and 'Trading Places'