Dave

Just finished rewatching the Dave episode of season 2. And the whole cloning thing fits in for that episode. Dave told Hurley that he was still in Santa Rosa and that everythng around him was not real. Did he mean the Hurley before him was not real because he was a clone and the real Hurley is in the hospital just like the real Dave and btw the real Libby who is sitting in a catotonic state a few chairs away from Hurley?

Real

Hurley in Santa Rosa
Libby in Santa Rosa

Clone
lottery winning hurley on the island
Psychotherapist Libby

So how does this fit in to time traveling? hmmm
There lies the rub

Dave was Libby's husband as well as the first dead guy that Hurley ever saw. in the season finale, during Desmond's flashback where he met Libby, she reveals her husband's name was David. Maybe Dave was worried of losing her love to Hurley and that's why he appeared on the island , trying to get Hurley to kill himself or maybe the island was messing with Mr. Stay Pufft even before the crash.

[Kathy Numbers]

I have a theory on this too.

Maybe Dave was a manifestation of the Skrull Locke (Fake Locke, Black Shirt - whatever!). He told Hurley to jump off the cliff. If Hurley had, the guy could come back as Fake Hurley and start stuff earlier and not have to wait around for Locke to get killed.

Dave wasn't just a Hurley halucination. Didn't Hurley find a shoe or something the guy left, proving at least to the viewer that the guy was somewhat real?

[drfitz44]

He found a shoe, but that could have been in his mind... Because Libby said that he didn't even have a shoe when she saw him...