Very interesting chapter. Even though the people wanting to see fights for their agenda won't be happy about it.
A few things about Sabo. He seems to be very fast with good ears or maybe some special applications of CoO like Enel. He heard the guards talking about a special room so we can bet he is going there to find out about it.
That's where he will see Imu and King Cobra's death. I'm pretty sure after that they unleash the Holy Knights on him or maybe Gorosei fought him themselves and that's how he was injured.
Then on the Shirahoshi's kidnapping, I kinda hope that Celestial Fucker is dead (I know he isn't) and good to see Sai and Leo attacking a CD just like Luffy.
Finally, the scenes with Cobra were good and we learned something new about the letter D. I hope to see more of that next chapter.