I loved the reuse of the music from S1 E6, where morty was shell-shocked from watching himself die. Now Rick has watched himself die, by his hand. Rick has often broken the fourth wall by referencing the different season numbers, so I think he was aware he was in episode 5, expecting his encounter with Rick prime to be a finale. But instead the insane writers planned it to happened mid-way, that we nor Rick was expecting.
Also can I just credit the new voice actors, especially Rick prime screaming, "YOU LIVED IN MY HOUSE", which was just perfect. You barely even notice the new actors anymore.
There was also one of the best end credit scenes we've ever had, showing how if Rick just let go, he could have had a happy life. But I guess it's just in Rick's nature, due to the existence of Rick prime's automated box. If only he was more like Mrs Mobius.