The spoiler I could've provided is that O'Neill gets forced into retirement and decides to return to the planet with the woman who wanted to have his baby, so they send him without an GDO, knowing he can never return, and that he stays there happily FOR ABOUT EIGHT SECONDS.
It was a well done episode, and in some ways even more impressive on a second viewing. Now that you know the con, you can see that General Hammond was acting
, and the difference is so slight, yet so there, that I was really impressed. It's just enough so that you didn't catch on during the first viewing, yet so obvious that upon a second viewing you think "How are Daniel, Sam, and Tea'lc not seeing through this charade?" Flip back to the first part of the episode and you'll see what I mean. It's an amazing performance not for its depth, but for its subtlety. I went, "So that's how a good actor acts like someone who's a good actor."
As an aside, in several episodes they mention his grandkids, but they never mention his daughter. As it turns out, his daughter is Dana Scully from the X-Files (several episodes). You could build a vast conspiracy around that one.