2) Even though I know these writers have a penchant for following the comics, making M'gann a White Marian feels like a misstep because I think there's a more interesting story that could've been told by making her the actual "Last Daughter of Mars". Going the route that they did also introduces an inconsistency in the way that they've handled Martian shape-shifting, as every time they've done it up until the very last scene of the episode, the person doing the shifting has reverted to their 'natural form' briefly in between shape changes. If you're going to go the route of making her Green Martian form a disguise, at least be consistent with your shifting effect and don't hold off the reveal that she's actually a White Martian until the last scene of the show
Ah, but have we seen a White Martian shape-shift?

The White Martian reveal was about the only interesting thing in a by-the-numbers episode.