Ben and Roger Linus are going to show up very soon then, because they were supposed to arrive sometime in the 70's and we are already in 1977!

I wonder if Ben's coming back screwed up the time line of his life. Can he exist on the island at the same time as kid!Ben? Perhaps that's the reason of his condition in the infirmery of the Hydra station.

The fact that Charlotte's body vanished might be a clue. Her corpse couldn't remain since toddler!Charlotte was already there.