In the movie I noticed two places where the number 9 was displayed. Once, when McCabe was interviewing David in prison, it was written on the right side of the chalk board in the background. The second time I noticed it was when they were entering the LE building, the building across the street had a large number 9 as the address. Also, Sofia tells David "I'll tell you in another life, when we are both cats". And, cats have 9 lives!
Also, does anyone know the years of the cars used, I think David had a 69 mustang...
