In 2004, Oceanic 815 crashes on an uncharted island. As the passengers try to survive, they begin to realize the island isn't a normal place. Jack locates the front section of the plane in the jungle, but the pilot is killed by The Man In Black in his smoke monster form. Sayid takes a group into the hills to try to get a clearer signal with the plane's transceiver, and gets a recorded transmission from a previous visitor to the island. One that's been playing for over sixteen years.

Jack fell out of the airplane and landed in the bamboo forest -- close to the location of the heart of the island.

The shoe in the tree that Jack passes on his way to the beach will still be hanging there three years later when Jack dies.

Boone suggests using a pen for a tracheotomy on Rose. In the post-afterlife 2004 reality, Jack will suggest the same thing when Charlie is choking on Oceanic 815.

Jack's "count to five" story that he tells Kate will be fleshed out further in the episode "The Incident."

Jin's "Don't worry about the others" assurance to Sun is a bit humorous considering how "The Others" will take on a different meaning in season 2.

We learn the name of the plane's pilot (Seth Norris) in "The Beginning Of The End." In that same story we learn that Frank Lapidus was scheduled to pilot Oceanic 815.

The backgammon scene with Locke and Walt is a strong teaser, planting the seeds for Jacob and The Man In Black's conflict seasons from now.

Sawyer holds up the marshal's star he took from Edward Mars. In 1977 his role as head of Dharma security will have him wearing a logo also with a marshal's star in it.

The polar bear was most likely from the same 'nest' as the one that later attacked and took Mr. Eko.

Here's a rundown of where various main and secondary characters are during this story:

Ben: witnessed the plane breaking up mid-air. Presumably he and Juliet went to see Mikhail to get more info about the crash that same day.
Juliet: witnessed the plane breaking up mid-air. Presumably she and Ben went to see Mikhail to get more info about the crash that same day.
Desmond: in the Swan hatch, still in the aftermath of the button being pressed late.
The Man In Black: has already taken on the form of Christian Shepherd. May have taken the casket to the caves that same day.
Jacob: unknown, though certainly aware of the plane's arrival.
Miles: unknown, probably on a job.
Richard: unknown. He might be off island on Mittelos Bioscience work; that would explain why Jacob's spokesperson wasn't around to make contact with the survivors.
Frank: nursing a hangover.
Daniel: unknown, though most certainly still houseridden.
Charlotte: unknown, possibly on archaeological duties.
Ilana: unknown, no theories.
Penny: unknown, presumably still looking for Desmond.
Eloise: unknown, no theories.
Ethan: sent by Ben to go to the beach to find out about the survivors.
Goodwin: sent by Ben to the jungle to find out about the tail section survivors.
Charles Widmore: unknown, no theories.
Danielle: unknown, presumably she was in her camp since she didn't have any clue about the plane's crash.
Alex: unknown, no theories.
Mikhail: at the Flame station, presumably finding out more about Oceanic 815.

The opening 8-minute scene with Oceanic 815's crash on the beach is still as intense as it was when it first aired.

Locke's smile to Kate when he has the orange peel in his mouth.

It's ironic that with so many of the Oceanic 815 survivors having met or seen one another in one form or another prior to the crash that Kate asks Charlie if they've ever met before: the two characters who haven't had any previous contact.

Boone's cell phone not getting any reception (as well as the airplane's transceiver problems) could stem from the Looking Glass underwater station jamming any signals.

When Kate says she saw smoke through the valley, she might also have been seeing The Man In Black in his smoke monster-form.

What was The Man In Black doing in the forest in smoke monster-form
the first night of the crash?
It hardly seems likely that he was just rampaging through the trees for no reason. My theory is that he was after Ethan. When Ben sent him to the beach he thought that Ethan might make it there by nightfall... which would be the right timeframe for The Man In Black's attack.

Was it The Man In Black in the forest during the second day that the
survivors heard?
My guess? No. For one thing, there were none of the familiar smoke monster sounds heard this time around. Not to mention that not long after that he would be attacking the Oceanic 815 plane and killing the pilot. My guess? It was either wild boars or perhaps the polar bear that later attacked Kate and her group.

Why did Oceanic 815's communications go out?
This has been one of the thorniest questions for me to figure out. Considering that the plane wasn't in the vicinity of the island until after the communications went out, it can't be because of the EMP-buildup from the Swan (or even from the Looking Glass jamming communication signals). The only possible and likely explanation is that Jacob is the one responsible for the problem. That sent the plane on a different heading, leading it right into the path of the EMP-explosion.