This is one I loved as a kid but as an adult I am left scratching my head as to how they got away with it. The Romulan ships would have had shields up except when transporting, they would have had sensors and weapons trained on the Enterprise. I think it needed an extra bit of mission impossible, an extra agent running interference, for their success to make sense. I think the script writers should have made a fraction more of Spock's 'inability' to lie in the wordplay.I was watching 'The Enterprise Incident' today and would definitely change it. I really like the Romulan Commander but thought it was too easy the way she fell for Spock's charms.
I have queries about the Federation's morality here. I'd have liked Kirk and Spock to have been more concerned about this. If I were to change the episode I would make The Rom Commander just the Captain of one of the 3 ships and would have Tal be fleet commander and commanding her to try to seduce Spock. She would object then agree and sort of fall for Spock and eventually they would lament together that they must do as ordered by their captains.
Ooh sorry gone into fan fiction mode but the Rom Commander came out looking like a bit of a fool and I would like there to be a reason for that. Perhaps her reason for jumping into the transporter was trying to pull Spock back or something.
The commander's reappearance in Star Trek Continues was pretty cool.