According to various Japanese anime and manga historians, the significance of Duke Togo's alias "Golgo 13" and the symbolism of a skeleton wearing a crown of thorns is this: Both refer to the "13th" Roman Soldier to take part in the crucifixion of Jesus Christ. Specifically, the 13th soldier is the one who puts the crown of thorns on the head of Christ. "Golgo" refers to the hill of Golgotha, where Christ was crucified.
The attitudes, methods, and mannerisms of the Golgo 13's character is intended to reflect the ancient Samurai. He is, in a sense, a modern Ronin.
Golgo 13's weapon of choice is the M-16 Assault Rifle, Model 'A2'. This is an update from previous anime and manga comic versions where he used the Vietnam War era 'A1' model.
While Golgo 13 will kill anyone he is hired without any moral qualms as to whether the intended victim is good or bad, Golgo 13 has one standing rule: He will never kill children. Even in instances with Reginald Rhoadeshere a child has been sent against him, Golgo never kills them. But he does kill their adult handlers. Though it has never been implicitly stated in the manga or anime, the reason for this rule is that he views children as the only truly innocent victims. Whereas adults are fully responsible for their actions.
Golgo is seen driving a red C6 Corvette in multiple episodes.