Clark Kent sees what the world would be like without him in a milestone of an episode, the 150th of "Smallville." Clark realizes that a lot of grief and sorrow has come through him. He is reluctant to go back in time to Krypton to save Kara, and himself, because of the bad that in his mind is all his fault. Because of this (constant) self-evaluation, he wishes he had never been born. Jor-El shows him how incorrect Clark is in making that wish.
Once he sees how much danger the world would be under without him, Clark decides to return back in time to Krypton.
While an interesting episode in a 'It's A Wonderful Life' sort of format, it's unfortunate to see Clark still blaming himself for everything that has gone wrong with events near him. However, after emerging from the alternate reality, at least he realizes how much good he has brought to the world, and how much worse it could be without him. However, scenes from Krypton at the end of the episode tamper with the previous episodes of the show and the very basis of the myth. Basically, the writers' decision to go with a back-in-time conflict infringes upon previous established and epic facts that will leave you loving or hating this episode. Fortunately, a lot of their fans liked it.
Nods to the classic Lois and Clark relationship from the Superman story and the Smallville Lois and Clark's future are touched on in the alternate reality, which is a welcome story.
