In Act 1, if you talk to the bartender at The Hanged Man then he may say something about the rapid decline in the pigeon population in Ferelden. This is a reference to Shale from Dragon Age: Origins.
Parts of Isabela's backstory mirrors that of Jack Sparrow from Pirates of the Caribbean. Like Jack, Isabela claims to be a pirate captain, but she has no ship. She is also confronted with freeing a cargo of slaves, which is how Jack Sparrow became branded as a pirate.
While in The Hanged Man with Varric Tethras he can be heard saying, "I like this bar, everyone here knows you name". This is a reference to the theme song of the popular American sitcom television series Cheers which ran from 1982 to 1993.
If you speak to Varric in The Hanged Man, he will make a comment about a serving girl named 'Edwina'. This is a reference to Baldur's Gate 2, where the mage 'Edwin' is turned into a woman at the end of the game.
During dialogue with Isabella, she will say, "I like big boats, I cannot lie." This is a reference to Sir Mix-a-lot's "I Like Big Butts."