After watching it with my girlfriend (who I've also gotten hooked on Firefly), she speculated about why and how the shuttle containing Zoe, Wash, Simon, and River returned to Serenity at the end. She thought that perhaps River could somehow sense that Mal needed them and it was her psychic abilities that are largely to credit for their return. I thought that was an interesting idea, and even more interesting that the episode made no mention of River playing such a role. So *did* she, or was it really due to Zoe that they returned? Any speculations?
By the way, sorry if this has already been discussed ad-nauseum. I'm still a semi-newbie to this fandom; today was the first time I saw this episode. (Am forcing myself to try to watch no more than one ep per week. This is requiring more discipline than I have).