Watching the scene of Viserion getting hit again, I wish Emilia would have made more of a reaction. People like to shyt on her acting, and I usually think her acting is fine given the character who is supposed to project an air of confidence at all times. But it would have been added more 'umph' to the death if she could have given more of a horrified reaction, perhaps something similar to when Elaria saw Oberyn get crushed.
Her scream is what always sells that scene for me.
Just like Cat screaming when she saw her son die sold that scene.
And Cersei screaming when she watched her son die sold that scene.
Both were horrified and vulnerable and destroyed.
As it stands, Emilia's understated sadness looks no more devastating than any of the other people looking at the dragon die.
Jon had more of an angry reaction, which makes sense because he probably feels guilty for getting her dragon killed but I guess I just feel now would have been the time for Emilia to give a performance that isn't so muted, especially since this is one of her "children" being killed.
She gave the muted performance when she sent Jorah away, and gave the muted performance when she finally made it to Dragonstone. Feels like a horrified anger would have been a better direction for that particular scene. And then they could have fell back on sadness when she reflected on the boat with Jon.