There are a lot of unanswered questions like will we see Claire? who is the other Locke? did the hydrogen bomb detonate successfully? These will all hopefully be answered in the weeks to come.
With all of the uncertainty and plot twists, there are a couple mysteries I would like to offer my theory for.
**Warning** Spoilers ahead!
1. The skeletons found in season one(episode "House of the Rising Sun") by Jack and Kate in the cave. They were given the names Adam and Eve. I believe that these two are the remains of Bernard and Rose. After it was revealed that they were still alive when the island moved to 1977, they are shown in the jungle with their own house.
2. The explosion of the hydrogen bomb in the final episode of season 5 is the "incident" and is also what causes the fertility problems that arise on the island. Before the detonation, mothers who give birth do not die. This is shown when Amy give birth to Ethan. But after the detonation (to our best knowledge) there are problems with childbirth.
3. I began to think about Charlotte being the red haired girl that Ben liked when he was a kid. But then I read somewhere that her name was Anne. So that is up in the air for now.
