The other episode I spoke of in the previous blog was Jughead.
Jughead was the third episode of season 5. At that point, a lot of us were just getting used to the idea of time travel and seeing things that will or have come up in the past now making sense. But Jughead was the first to give us some huge answers in the way of back story.
Where once Lost had used flashbacks for story telling, these jumps allowed the show to experience literal flashbacks and not just memories. And with these Jughead revealed huge pieces of information about the island's inhabitants.
First off, Richard is still the same age, the others know Latin and wear WWII uniforms, there is a hydrogen bomb on the island, and Faraday loves Charlotte. But the biggest surprise was that Charles Widmore was once an other. The next day at work everyone was talking about this. It was huge in the implications it had on Widmore's motivations and methods.
Jughead set the stage for the season finale as well as what kind of story we were to see throughout the season. Though, reruns of the episode won't be as powerful, the episode still rocked.