I am an expert in authenticating Balenciaga's bags, especially the lariat/motorcycle line that we all love so much! I've physically inspected hundreds of Balenciaga bags from '01 through S/S '08 (I haven't received my Fall bags yet ;o) I've been collecting these bags for many years and personally own a vast collection illustrating each and every season. I have also seen and touched counterfeit bags and even the best of them have details that are wrong, usually it's lower quality leather, different hardware, incorrect fonts and less craftsmanship.
I have received the S/S '02 Black First with the upside down buckle (on the left side) and the Pierre Cardin lining on the interior pocket and upon physical inspection I believe it to be 100% authentic Balenciaga. I personally own a S/S '02 Chocolate First and shot comparison photos of them to show how everything aside from those human errors match up. These early bags were handmade in Italy and they do show variations from bag to bag depending on the craftsman who made them.
S/S '02 Black PC First versus S/S '02 Chocolate First:
^ note the same strap o-ring closure style, chunky clip hardware, square-shaped buckles, brass rivets and stitching tension and human variation.
S/S '02 Black PC First versus S/S '02 Chocolate First, plus S/S '02 Black Hobo mirror:
^ note the mirror grommets are the same on the Black First and Black Hobo; the hardware that attaches the handles is identical on both the Black and Choco Firsts as is the wonky handle bend above the rivet, near the whip stitch knot.
S/S '02 Chocolate First versus S/S '02 Black PC First interior pockets:
^ note the hand stitching variation on each interior pocket and even placement of the branding tag, but the unique design is the exactly the same.
S/S '02 Chocolate First interior pocket and branding tag close-up:
S/S '02 Black First PC interior pocket and branding tag close-up:
S/S '02 Chocolate First top zipper close-up:
S/S '02 Black PC First top zipper close-up:
Let me know if you'd like me to show anything else in pictures while I still have this bag here before I send her back home.