In answer to what the 'real' blue key opens the hitman starts to laugh. This is bugging Diane - so in her dream she finds herself an answer by creating the blue vessel.
I believe that just before the Magician disappears at Club Silencio, he causes the blue box to appear in Betty's purse, although we don't see it until Rebekah sings. Perhaps the evil Magician represents the person behind Winkie's (Lynch uses the same type of lighting in both scenes) who is slowly forcing Betty/Diane to face the reality of what she has done (also what she has become), as represented by what's inside the blue box. - (humanist)
Notice how once the blue box appeared in Betty's purse and her shaking, Rita stopped holding her hands at Club Silencio. The self-delusional dream was already unraveling to reality. That's why Betty disappeared. Because Betty does not really exist; she is an idealized or former shinier/optimistic Diane in her real hopes and dreams, unfulfilled/unrealized (even in the dream). Rita is Camilla/Diane together as one, representing Diane's wishes/confusion. I don't think Rita being sucked into the box is saying that Diane desires to kill her again. It's symbolic of Rita finding out the truth by turning the key in the box, like metaphorically saying Betty/Diane is found out by Rita/Camilla of the truth... that Diane indeed killed Camilla in reality. - (Misslinda77)
[…] The blue box then appears in Betty's bag. An explanation of its appearance is unnecessary at this point; the dream narrative abandons any attempt at consistency when Rita awakes mouthing 'Silencio'. They hurry home, impatient to see what is in the box. Rita retrieves the key, and Betty abruptly disappears. Rita, after a perfunctory search for Betty, takes the key, opens the box and disappears too. Rita and Betty are also illusions, products of Diane's dream. The illusions of dreams and of show business are compared. The blue box symbolises show business. It glows an otherworldly shade of blue, irresistible, impenetrable except to those with the talent to unlock it. Once opened, it consumes all, as it does Rita, yet it is empty - again, we are reminded that there is nothing of substance inside. - (bunter)
the scene at Winkie's, when Diane asks the hitman "what's it open?"
the hitman is just laughing. But watch his small gestures: he starts laughing,
puts his head slightly to the window and is clapping with his right hand on the
windowsill. When you look out of the window you can see it across the street:
the blue dumpster - just
above the hand of the hitman.
Thread: I found the key piece of puzzle - (kar)
has been remade to look like Betty, to become Betty, so there is no reason in
the dream for Betty to remain. She disappears just before Rita uses the key to
unlock the box - another representation, interestingly, unification, of two part
becoming one, and in the process completing one quest and opening up another deeper
The Betty persona cannot face the moment that the key and the box are finally present together. Together they represent the knowledge of the horrible act that has condemned Diane to a guilt-ridden existence.
Betty, who represents Diane's innocence, cannot survive this truth. Certainly opening the box which represents this truth would have destroyed
her. But the innocence of Betty was destroyed even before the moment the box was opened. This is because when she brought the blue box into the bedroom she immediately put it onto the bed. This connection to the bed forces Betty to confront the other awful truth that was exposed in Club Silencio. The electrifying scene of her going through spasms as she is
being raped as a child is what destroyed Diane's innocence long ago.
The most interesting example of this unbreakable cycle of dreams - the idea that reality is as empty as dreams - is embodied by the blue box. The mysterious blue box in Mulholland Drive seems to represent the answers to the film's puzzles. Rita finds the key in her purse while looking for her identity; she believes the box it opens will contain the answer. However as the camera travels inside the box we see it contains nothing. At the end of the film, the monster behind Winkie's is seen contemplating the box before he throws it down with the rest of his garbage; it seems to mean nothing. The problem of the small, square blue box is compounded by the existence of a second blue box in Mulholland Drive. Betty decides to hide Rita's purse, money and blue key, representing the mystery of identity, within a tall, cylindrical hat box: yet another blue box. After the scene at Club Silencio, Rita retrieves the key from the blue hat box and uses it to open the square blue box. Lynch is demonstrating that the box cannot hold all the answers, it merely poses more questions. - (John DeCarli)
The blue box is a detail which comes straight out of the work of French psychoanalyst Jacques Lacan, a major influence for Lynch. Lacan describes this exactly: "Suppose you're dreaming about yourself disguised as your desired self/other and you open a box with a key to find only darkness, your dream will collapse, and you'll wake up to find your real self. That's the situation as it occurs in dreams. But when you're not dreaming, and you open that same box, your psychosis has just killed you." - (shonagon53-1)