Portal easter egg
Note: Sten must be in your party for this to work. At the end of the game, if you choose to perform the ritual with Morrigan, you will go to the coronation of the new king or queen. After the dialogue with Alistair, you can walk around and talk to your companions. Find Sten and he will say "Where is the cake? They promised there would be cake. The cake is a lie...", a clear reference to Portal.