Locke with his orange in mouth smile is definitely an omage to The Godfather but I am not sure if LOsT is using it to foreshadow a death scene. I thought they used the color red for that. Like right before Eko's death scene his is talking to Yemi in a field with several red flowers.

As far as other orange appearances, didn't Hurley drive his camero through a bunch of oranges at the beginning of the first episode of season 4? It was some kind of fruit, I think it was oranges.

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Doctor playing golf. Woo, boy howdy, now I've heard everything. What's next, cop eating a donut?