S10E5: Back to the Pilot
Oh, God, my leg is killing me.
Well, time travel is risky.
Every time you step into that machine,
you invite the possibility of altering the world as we know it.
Thankfully, the alternate versions of us were there to prevent us from doing whatever it is we apparently did.
I wonder what it was.
We'll never know.
But look on the bright side.