This episode was pretty much entirely original to PGSM. All the stuff related to Minako being a pop star is obviously original to PGSM. The stuff related to Minako being Sailor V may have had some basis in the Sailor V manga, but not having read it, I'm not sure - in any case, there was very little of it that didn't related to the other Sailor Guardians, who of course weren't in the Sailor V manga. Zoisite and Nephrite's activities continue to have nothing in common with their activities in the manga. Even that cool moment of revelation that Tuxedo Mask had towards the end has no basis in the manga (except that the content of the dream still relates to the manga story, of course).

However, the idea that Minako is the Princess comes from Act 8 of the manga, and this episode clears up an ambiguity found in the manga story. It is made explictly clear in this episode that in PGSM, Minako whole-heartedly believes that she is the Princess. Whether Artemis believes this is not clear, though.

However, deviating from the manga is not inherently a bad thing, as this episode proved I think. It was a lot of fun, and it had that very cool scene with Tuxedo Mask near the end. I also like how they're handling Minako as a character, including the idea of her being the Princess (which I'll talk more about in my comparison for Act 12).