Of course just because TV or film writers have read some deep books, doesn't make their work deep. I thought the first Matrix hinted at some interesting ideas rooted in Gnosticism, but we all know where that ended. Perhaps the ideas don't stick, or perhaps the constraints on the writers stop them from realising the ideas. I'm not saying Lost will fail like the Matrix though.
A good book which goes into the Bardo in more depth is 'The Years of Rice and Salt' by Kim Stanley Robinson. This is an extended alternative history of an Earth where the black death more or less killed all Europeans, so China and India became industrial powers, and fight a big war. The main protagonists are killed and reborn from the Bardo many times.
The Bardo is said to be inhabited by massive frightening entities, which are however a projection of one's own fears and obsessions. I have just flicked through 'Years of Rice' to find a good description of ther bardo, but I can just find this, which shows some of the overlap with 'Lost':
In the deep southern canyon they found themselves in a different world. Indeed Bai had to reconsider the idea that he was in the bardo at all. If he was, this was certainly a different level of it: hot, wet, lush, the green trees and bushes and grasses exploding out of the black soil and overrunning everything.... Perhaps Kuo had lied to him, and he and the rest of them here had been alive all the while, in the real world made deadly. What an awful thought! The real world become the bardo, the two the same...'