This episode presented the first alternate universe in Atlantis canon; though it ended tragically for this version of the expedition, the writers returned to this theme many times over the course of the series. Personally, it's one of my favorite themes in fan fiction. I love all the "what ifs" out there.
Out of power and out of time.
Weir: Can you fly those ships?
Sheppard: I can fly just about anything.
(Just a gorgeous shot of Weir.)
It's not a DeLorean but it'll do.
McKay: Well, a man wonders how he would choose to go out, given such dire circumstances. Now I know.
Sheppard: We're in space! What happened?
Sheppard: Hang on!
"Before I Sleep" 1x15