I had a feeling the list was gonna be explained this season due to time travel.
Another plot point that was planted very early on was Jack's dad being alive on the island. Jack saw him in an early episode.
I think they have a broad story mapped out, with important plot points that need to be reached at the end of each season. How they get there and what happens in between, they improvise.
What do you want to bet it was a production crew member, the director hoped no one would notice him and now the producers are saying "oh shit, now we have to write an explanation for this"?
Well, that's exactly how Bob was introduced in Twin Peaks.
