What happened when Juliet detonated Jughead? (5×16/17)

Background: In 1977, Daniel Faraday reveals a way to reset everything that has happened since Flight 815 crashed. He told Jack that, if he could drop Jughead into the pit being drilled at the construction site just as the drill hits a pocket of electromagnetic energy – the same energy that would eventually bring down Flight 815 in 2004, that they would wake up safe on board Flight 815 like nothing had ever happened.

Answer: It created a parallel universe!

• In one universe, the detonation of Jughead didn’t work, the Swan Station was eventually built, Desmond is late entering the numbers, Flight 815 crashes. The characters who were living in 1977 are transported back into the 2000’s, sometime after the destruction of the Swan site.
• In the other, Daniel’s plan worked and Oceanic 815 never crashes, they carry on with their normal lives. Boone, Charlie, Edward Mars (the Marshall), Arzt and John Locke are alive and well on board.

What’s in Hurley’s guitar case? (5×16/17)

Background: After leaving the Island, Sayid breaks into the mental institute where Hurley is being held and shoots a guy. Hurley then travels with Sayid to his safe-house. Inside they find two intruders, Sayid kills them both but Hurley is pictured with a gun. Although he didn’t commit the murders, he confesses to them – he wants to be locked up so that he is safe from Ben. After being released from prison, he shares a taxi with Jacob, who leaves behind a guitar case.

Answer: An Ankh containing one of Jacob’s "lists" and a note that, if Sayid were to die, they’d all be "in a lot of trouble".

Why is Jacobs Cabin surrounded by a line of ash? (3×20)

Background: In Season 3, after killing his father, Locke demands to see Jacob. Ben takes him to Jacobs cabin, which is surrounded by a line of ash.

Answer: It seems that the Smoke Monster can’t cross lines of ash. In the Season 6 premiere, when being attacked by the Smoke Monster in the base of the Statue, Bram creates a circle with ash and stands inside. He is safe inside until the monster influences the environment around him and knocks him out of the circle.

What is the Monster? (1×01)

Background: In the Pilot, Part 1, we hear a mysterious sound in the jungle. We find out in Part 2 it has killed the pilots of Flight 815. In the Season 1 finale we first see it as "Smoke" as it attempts to drag Locke underground. In episode 5 of Season 3 we first see it take on the identity of a human, when it appears as Eko’s brother Yemi – and then kills Eko.

Answer: The Smoke Monster is "Jacob’s Nemesis" – "The Man in Black (MiB)" – "UnDead Locke" – "Fake Locke (Flocke)" – we don’t actually know the guys real name yet, all we know is that a long time ago he was a friend of Jacobs but grew tired of his company, and now for some reason wants him dead. To accomplish this, he took over the body of a dead John Locke. John Locke’s body is the the Smoke Monster.