I had two favorite parts:
1) a tribute and recognition of Cannell's role.
2) "Stop confusing me with your reasonableness." -Castle to Alexa.
On Hawaii Five-0
* I love the continuity continuing even here! (mention of the CIA agent, of the stolen money, etc)
* So Chin fell on his sword and took the blame so his uncle wouldn't be punished. Interesting. And very believable, given what we know of Chin.
* only saw the first half of the ep, but I have a feeling that the body was set out on that ledge as bait for McGarrett - he outright told Danny that he goes there every year at that time of year.