...Curiously, the other window shows a wall with a grillework that closely matches that on the interior set. Which is good continuity, but the grille in the set is rather down low, below shoulder level, suggesting that the guy peeking out is crouching deep down, or a dwarf!
The apparent floor level indicated by the docking port establishes this already anyway. What was Probert thinking, placing these portholes so low in relation to the doors? Perhaps he assumed that the interior set would have stairs not unlike those found in the "topside docking port" set through which Spock enters?
They appear to be in a separate space, perhaps between the hulls. Makes you wonder why there's the portholes there and what exactly in in that space. And how do you get in and out of it anyway.