Movies set in the same World/Universe that people don't realize

What are some good examples of movies that are actually connected that most people are not aware of?I recently discovered that Jason Statham's character from The Transporter franchise shows up in the movie Collateral (2004).Another example which is a lot more obvious but still goes over many people's heads is that Machete is actually a spin-off of Spy Kids. via /r/movies https://ift.tt/KXYcizQ