In episode 16 ("The Burning Desert Sands"), it is made very clear that the main character Kira Yamato and his love interest Fllay Allster had sex sometime between episode 15 and 16. This scene gave parents in Japan a scare and caused a good deal of controversy at the time.
The Captain of the Archangel Cpt. Murrue Ramius is loosely based from Tom Clancy's The Hunt for Red October character named Marko Ramius. Fittingly Murrue Ramius also ended up defecting to the nation of ORB just like Marko Ramius' defection to the US.