1. The Hatch.
Oh, Locke's epic quest to open the hatch. He himself told his fellow castaways that the answers were down the hatch. In certain respects, he was right. In other respects, he was wrong (as the plot went down the rabbit hole on the Dharma story arcs).
The Hatch had the potential to be the game changer. It set forth the following points:
a) There was an advanced technological people who inhabited the island in the recent past.
b) The Numbers were embedded in the island's past history through the countdown timer.
c) The hatch computer seemed to control the "unique" electromagnetic properties of the island, which we were led to believe in the end was the Light Source.
d) It gave us the first "orientation video." This was the introduction of the scientific experiments that the Dharma group was conducting on the island. It began the connection between the polar bear, and future stations showing brain washing and human experimentation. Some fans concluded that the island was one large psychological facility (which leads to possible explanations such as the characters being institutionalized and programmed to believe they were on an island.)
2. The Blast Door Map
Instead the Hatch was the treasure trove of set design: the blast door map. When Locke, the keeper of the Hatch protocols, got trapped under the blast door during a drop, the blue light revealed the details of the island map. This was probably the most focused HD screen shot of the series.
3. The Egyptians
There became an overriding set design with Egyptian hieroglyphs during the latter part of the series. One had to see that all the background glyphs were created in extreme and accurate detail - - - so they had to be important to the story line. Many of the Egyptian writings were about life and death, Egyptian burial rituals, and the ancient beliefs in the after life. While the producers-writers dismissed the notion that the characters were in "purgatory," the use of so much Egyptian mythology in the sets, including the temple and its life spring, made many believe that despite what TPTB were telling the world, the filmed episodes clearly represented a potential journey through the after life.
4. The Lighthouse
The last great clue was Jacob's Lighthouse. It also contained hieroglyphs, but this one came with an explanation from the immortal leader. The lighthouse had a dial which could be turned to view the past lives of the "candidates." The clue that the people who came to the island were not accident victims but intentionally culled and diverted to the island by Jacob alone brought a new realm of theories to the fan community. A candidate is a person seeking to hold a position or office. A candidate who obtains that office usually acquires power or control over something important. This was part of the story arc of Jacob and his brother, both diverted to the island in ancient Roman times by a Crazy Woman who was seeking her own "candidate" to replace her endless guardianship of the island. In the end, Jack reluctantly became the new island guardian to help slay MIB-Flocke from escaping to allegedly "destroy the world." But the final plot never explained the elements, purpose or powers of the guardian had over the island's heart. It also did not explain the sideways world or the show's conclusion.
These four items were the viewer launch points to various show theories which sustained them from episode to episode, series year to year.
