Kid_Eternity said:
I thought it was just as shown on the screen...
*LOTS AND LOTS OF SPOILERS*
There are quite a few clues to suggest that she might be dreaming/hallucinating.
Just prior to waking up from the crash she is dreaming of her young daughter blowing out the candles on a cake. She then 'wakes' to find herself in a strange hospital environment lit by an eerie green glow.
After running through darkened corridors getting more and more hysterical (with the green light following her, leaving voids of darkness behind and ahead of her [and if I remember rightly with the vague sound of a child's laughter in the background]) she comes to in a crowded corridor collapsing in the arms of a friend.
Visually the suggestion of tunnels, claustrophobia and madness is established, and associated together, very early on.
Those motifs of the dream with the birthday cake and the vague sound of a child's laughter are repeated throughout the film and are generally associated with the horror soon to arrive.
From that you could argue that she never woke up from the crash and is in a coma/dead and experiencing an imagined reality. You might even go as far as to say that the laughter is that of her daughter (possibly alive) by her bedside, hence its unreal nature.
Such a possibility would be pretty terrifying. You go through a traumatic car crash, lapse into a coma and spend the rest of your days living out the insanity that you have descended into and created for yourself, out of the emotional pattern of jealousy, betrayal and anger that characterised your last 'waking' experience (the argument with the husband in the car).
But beyond that there are suggestions that even in a scenario in which she had actually woken up, she might descend into a hallucinatory madness within the caves and kill her friends out of paranoid self-delusion. For starters she experiences a number of hallucinations throughout the film, she is clearly on some kind of medication which she is shown to leave behind before she sets off for the cave, she is the first to spot the creatures and their existence is established mainly through her 'unreliable' witness (e.g. camcorder); and throughout the film much is made of the possibility of hallucinating in the pitch black of a cave.
As you can see, I quite like it and thought it had quite a bit of depth to it. Did anyone else notice the visual echoes and nods to other films throughout? Carrie was probably the most obvious one, but I also saw elements of Ringu when they first descended (the entrance resembling the well), Dracula, the evil dead etc....
p.s. just remembered the Blair Witch Project reference too, maybe we could try and list them all, there are supposed to be a ton of them.