The Empire Strikes Back Reference
When you play as a Smuggler, upon getting your Starship you will see a familiar sight in your Cargohold: Han Solo frozen in a block of Carbonite!
When your coming down the path from the Nebray Garrison, you will come across the crashed Millennium Falcon or Millennium Falcon look-alike.
Chewbacca Playing Chess With C3P0
When in Nemro's Palace on the planet Hutta. In the Cantina you can see a wookie playing a gold plated robot in chess. The wookie has also proceeded to tear off the robots arms most likely because he was losing.
While questing on Coruscant as a Jedi Consular, there is a scene reference to George Lucas's first movie, THX-1138. The Jedi Consular enters a dream state from a Datacron during one of his/her class quests entering an area surrounded by hooded men with robot faces wielding vibroblades. The area is completely white with no boundaries, much like the prison in the movie where Robert Duvall's character was sent to.
EVE Online Reference
When running the Republic Flashpoint: The Esseles, if you hover your cursor over the First Officer, you will see that his name is Plex. Which is the name of the EVE Online game time that you can purchase.
Check out our comprehensive Star Wars: The Old Republic Tips Guide.