It was never a stolen Romulan Bird-of-Prey even late into the writing process -- that was merely a notion that Harve Bennett batted around very briefly during the story-brainstorming sessions prior to production, and the notion never survived into the actual final shooting draft. It was only ever an early conceptual idea at best.ChromeJob said:Again, in ST III Lord GiveMeTheSecretOfGenesis stole a Romulan vessel prior to meeting the merchant ship (hence the Romulan cloaking tech, though this was supposed to be adapted to Klingon ships in "The Enterprise Incident.). It never made it into the finished film.
Yes, it's an anachonism that Klingons would have a shp with a Romulan style bird of prey painted on it. (Stiles talked about it in "The BAlance of Terror" as a fabled way to recognize Romulan shps.)
(Besides, as we canonically see onscreen, it couldn't possibly be a one-of-a-kind, stolen Romulan vessel, since we get Sulu instantly -- literally in the space of about two seconds -- identifying it as a Klingon ship. )