Virtually all of this episode is original to the live action series.

In both the manga and anime, Kunzite was just there - the idea of him living as an ordinary person without his memories, and becoming Kunzite, is totally new. In the manga, Kunzite first appeared in Act 5 and first met the Sailor Soldiers in Act 8. In the anime, he first appeared in Episode 22 and first met the Sailor Soldiers in Episode 33. Naturally, Kunzite looks totally different in PGSM to in the manga or the anime.

The situation with Shin is an interesting one - Shin seems to be in a fairly similar situation to Mamoru, which makes sense given the link between Mamoru and Kunzite. I wonder if the idea is that all four of the Heavenly Kings were reincarnated as ordinary people, and Beryl awakened all of them in ways similar to this? That would be similar to the manga, where it was explained in Act 9 that the Four Heavenly Kings were reincarnated to look for their master, but fell into Beryl's clutches. Queen Beryl modifying Nephrite's memory also fits with this - and, in my opinion, is quite creepy. She's happy as long as they show love for her, but they will only do that if she makes them forget about things that might trigger memories about their past lives. I continue to find Beryl more interesting in PGSM than in the manga or anime.

The idea of Sailor Venus having her own mission as the Princess is original to PGSM. In the manga and anime, she revealed herself to be Minako right away (but they didn't know who Minako was beforehand, unlike in PGSM), and there was never any question of the other Soldiers protecting her, the Princess.

Usagi spent a lot of time with Mamoru in this episode, for the first time so far in the series, and the two of them began to get on better. In the manga, Usagi and Mamoru's arguing was more playful from the beginning, and it was in Act 7 (when she discovered about his identity and his motivations) that Usagi decided she didn't hate him so much after all. The anime had a lot more interaction with Usagi and Mamoru over the course of the first 34 episodes, some of which was similar to the events in this episode of PGSM.

Finally, Usagi getting possessed by a monster or turned into a monster is unique... I don't believe it ever happened in the manga or anime (certainly not in the Dark Kingdom arc, anyway).