"Kobra! Attack!" is a nod to Cobra Commander's battle cry from G.I. Joe: A Real American Hero.
M'Gann is confirmed to have found peace with her identity. Unless she needs to be Megan Morse on Earth, she takes the white skinned version; which her mother realize is the "true" form of her daughter. A regular White Martian, the Green humanoid Martian and the white bald version were all identities that did not reflect the real M'Gann.