What about Tsunade being cut in half?
Although that would go more towards Hashirama and Tobirama...

I never saw him and Hidan fight but I knew that he died
I also never saw the Pain Vs Naruto fight yet because that's too long..
Now that I think about it, a lot of people don't know their comrades are dead.
Sakura doesn't even know Tsunade is dead yet, and it's really sad that no one even cares about Yamato or Anko.
Completely forgot about that, how will react when he finds out Jiraiya is dead :O