The Great LOST rewatch is rapidly coming to an end, and after this season it feels like it couldn't come soon enough. While there may be a number of things to enjoy in the fifth season, for the most part it was 16 episodes of screaming at the TV about time travel.
I know it sounds unbelievably pretentious, but if you ask me, there are only two ways to write a time travel story. Either you explain the mechanics and rules of the time travel so well that everything tracks, or you don't explain it at all so no one can poke holes. For the most part, you're best sticking to option number 2. LOST however, plows head first into option number 1.
Brace yourselves. It's gonna get ranty.
Here's the thing about time travel in the LOST universe: it doesn't seem to have any rules. Not "it doesn't follow it's own rules," it doesn't seem to have ANY. Or, if it has rules, they make no sense next to each other.
Let's start with the very beginning of the season. When last we left the island, Ben had turned a giant wheel at the Orchid station, zapped himself to the future (he ends up in 2007), and starts the island on a time hopping journey all over the damn place. For those off the island and far enough away, the island seems to disappear, and when they return three years later, they return (mostly) to the 1970s, where those who were on the island when it moved in time are currently. This suggests that the island can only exist in one time. If you're on the island in the 1970s, then anyone outside that specific moment in time cannot see it. Fine, that makes sense, until you add people.
When there are people on the island, the time travel seems to only affect a select few, specifically, those on the island the moment the time travel event was triggered. They are apparently the chosen few people who are allowed to travel along with the island. Okay, fine, still sorta works. Maybe there's something that affects the island that also affects the people there at the time, like a bubble. But then we start trying to explain things.
When the Oceanic 6 (or, like, 2 of them) find Faraday's mom, she starts to explain the shit out of how the island works. The main element of those explanations: that the island is constantly moving in time in order to protect itself. If this is true, then there are a whole lot of questions that really start to ruin the already annoying time travel storyline.
If the island is constantly moving in time, then why did it need a person to make it move when it was threatened?
If the island is constantly moving in time, then why do only some of the people move with it? Either everyone should move with it, or no one should.
If the island is constantly moving in time, then why didn't it move at all (that we're aware of) during the three months they were on it before?
If the island is constantly moving in time, then why didn't it continue to move once the remaining castaways got stuck in 1970-whatever?
If the island is constantly moving in time, can only exist at one point in time, and the secondary island also disappeared with the primary island, they why did Sun, Ben, and not-Locke end up on the secondary island AND manage to find their way to the primary island IN THE PRESENT?!
I know. Maybe I'm nitpicking, but these things are annoying. Like I said, if you're going to bother to explain the way time travel works in your universe, especially if you're going to go to the trouble they did, you better make damn sure the explanation tracks. These aren't even deeply disguised issues with the explanation. They're literally sitting right on top, waving at you, wearing a neon sign that says "PARADOX".
And don't even get me started with the Hydrogen Bomb.