There is the 2nd episode where Locke is setting up the board of Backgammon and Walt comes to him and asked him what it is, and Locke explains the game, the origins of the game and focuses on the black and white pieces as being opposites of each other. Then there is Clairs dream a couple of episodes later where Locke has the White and Black eyes.

It's clear that they used these moments to come up with the last season... how they ended it though...



That's kind of why I'm watching it again, I'm trying to find where the show just went completely off the rails.