Symbolization

Although the end of the Mulholland Drive is about what is happening in reality, it still evokes plenty feelings of helplessness and confusion. Taking the blue key and the elderly couple as examples, several things have made the audience confused.  

key

What does the blue key mean and what does it open? The blue key appears several times both in Diane’s dream and in reality. In reality, the blue key is a secret code between the hit man and her after the murder. Diane is frustrated by the feelings of guilt and fear when she sees the key because she will find out whether Diane died or not by using it to open the blue box. In this sense, the blue key can not only open the blue box but also open the darkness, the worst parts in Diane’s soul. Some people suggest the blue key also represents several other things such as searching, penis, love, fear and murder. Furthermore, according to Dream Dictionary, “To see a key in your dream, symbolizes opportunities, access, control, secrets, or responsibilities. You may be locking away your own inner feelings and emotions. As with most dreams, look for the obvious connections by comparing the details or the theme of your dream to your daily life. Are you trying to figure something out and "unlock" a puzzling question? Do you wish to hide something? Are you locking something up or are you opening the door?” (Dream Dictionary) 

THE ELDERLY COUPLE

If someone looks back the last 10 minutes of Mulholland Drive, he probably will question why the elderly couple appears again and what the identity of the eldly couple is. Some people believe the elderly couple represents parental figures. There is another opinion says the old couple is just an excuse for Diane to comfort herself. “When things do not work out the way Diane has hoped, she concludes that she was the victim of some scheme by the seemingly kind couple.”(Lost on Mulholland Drive) 

  It is more interesting if you consider this couple as Adam and Camilla. Their appearances are pretty much similar and you can also explain why the elderly couple chasing Diane in the end of the movie by using this theory. They are seeking vengeance because Diane had them murdered.