I only did the first three quarters and divided them into two categories:
I might be wrong about some stuff.
Stuff that was obviously answered or isn't relevant to anything larger than trivia:
The monster killed the pilot because he didn't want people to leave the island. Christian Shepard's body could have been knocked out of the coffin during the crash. The psychic was lying to Claire. The sound the smoke monster makes is really pretty irrelevant. The horse is on the island from the Dharma initiative. Henry Gale got buried under his balloon. Libby's story isn't relevant. The four toed statue was built by the Egyptians. The reason why you need a specific compass bearing to leave the island is because the electromagnetic properties screw up magnetic equipment--of course, that doesn't explain anything else about the island moving. Tom wore a fake beard presumably to disguise himself if he were caught, same as Ben impersonating Henry Gale. Libby's previous husband was irrelevant. The skeletons in the polar bear cave were Mother and the Man in Black's body. Locke and Eko presumably got blasted out of the hatch when it exploded--how they survived, no idea. Locke presumably couldn't talk after the explosion because being in an explosion hurt his throat. Eko's entire plot got cut/rolled in to other stuff. The Russian letter in Mikhail's typewriter was irrelevant. Why the supply drop menu was hidden behind a game of chess is irrelevant, presumably it was another Dharma psychological experiment. How the Monks at Desmond's monastery knew Eloise is irrelevant. Ben saw his dead mother because he was having a vision or because Smokey was occupying her form. What happened to Ben's childhood friend Annie was irrelevant. Desmond's false vision of Claire and Aaron leaving the island wasn't explained, but who says he wasn't lying to Charlie about it to begin with? Mikhail didn't come back to life--the one time he almost died was when he went to the sonic fence, and they later explained it wasn't set to lethal force. Who knows whose eye was in the cabin window besides Christian Shepard. Naomi's bracelet doesn't matter. The time difference on Faraday's watches was because the island distorts normal time. Ben wasn't surprised that they were able to kill Alex, he was surprised that they were willing to kill Alex. Jack saw his ghost dad in LA because he was nuts and hallucinating. No idea why Smokey as Horace directed Locke to the cabin, but it's not relevant. The Oceanic 6 name Charlie, Boone, and Libby as the other three survivors presumably because they wanted to come up with a believable story. Why Miles decides to stay on the island is irrelevant. Ben makes the Oceanic Six come back to the island both because he has to for Jacob and because he thinks it'll make him head of the island again. The men who tried to capture Sayid and Hurley were presumably working for either Widmore or Ben. Ben talking to the butcher was talking in code about non-island members of the Others. I think Ben took C4 out of his vent. The Smoke Monster wasn't at the Temple, he was near and under the Temple. Presumably because he was trying to get in. The second flight had to have the same people as the first flight so that the right people would time travel to cause the events that led to the events that caused the first flight to crash.
Stuff that didn't get answered:
The supply drop went unexplained. The Others child/fertility story ended up unresolved. Walt's special powers ended up unresolved. I have no idea why Jack wasn't on Jacob's list when he was doing Ben's surgery, I asked that myself--but I assume it's because Jacob originally was planned to have a list of candidates to replace Ben (which is the direction they were going with with Locke's story) but that changed in the end. I have no idea about the fertility thing, that's a serious plot hole. Juliet getting branded when she was found guilty was part of the Others justice system--remember they even had that Sheriff type figure? That never got elaborated on in the end. The rules between Ben and Widmore were never explained and is a serious plot hole. No idea how Christian Shepard appeared on the freighter. The frozen wheel isn't explained, but the Man in Black basically says "it's a wheel that moves the island and uses magic light" so that's good enough for me. They never explain who is shooting at the gang during the time travel. Eloise's elaborate pendulum / island finding system isn't explained but presumably from her association with Widmore and his lifelong goal of getting back to the island, they were connected. Actually, most of the stuff done by Sun's father / Widmore / Eloise was clearly something they planned to explain at one point and then decided not to.
