Arya and Hound somehow got the news that Joffrey was dead but it didn't seem like they got the whole story, since she should have had some sort of reaction to the fact that her sister was not only assumed to be in on the plot to kill him but is also a Lannister. It would have been nice to see a little sibling rivalry: "Sansa always got everything I wanted; it's not fair! She even got to kill Joffrey!"