The only thing I can think of with the plane, is that when it crossed what I'm calling the Vortex, it actually ripped the plane into the two times. Causing one to be left on the island the Past side, and the other on the present time side.
However, they are using the time thing quite liberally.
I just realized something:
The professor told Desmond to give him information in the past, and he had it in his notebook! Well, that would mean that Desmond was able to go BACKWARDS in time, to the point of the professor's younger self. And yet:
When Jack and Kate are in a FUTURE to the island's time, they refer to the island in the past tense.
That illogical writing has placed the island in the middle between the past, (of the Professor's younger self), the future, (Jack and Kate after a supposed rescue), and the island, in which Jack and Kate are still on the island, as is the professor.
In conclusion: The writers have quite obviously taken such liberties with the laws of physics, that they are suggesting that there are 3 times existing at once.

I believe that artistic license has become too confusing, and may become the downfall of the show!

In the first season, the plot was slow and jumbled. Everyone watched just to see if it would actually lead somewhere. And to see if the plot would be defined.
Season two comes along,; A writers strike later, and everyone is even more confused! Hey writers, how many dementios of time and space are you going to create?
Well, that's all I've got to say about that for now.
I AM here Now, I AM Then, and I AM in the future! That's LOST!

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