Is that a dickey that the fellow second from left is wearing? If so, I imagine that he arrived at the golf game straight from the office.

Is that a Pittsburgh Pirates fan, dark suit, sanpaku eyes, sitting on the fence beside Mr. Penetrating Stare?

Birdie and Mulligan.

Some of these shirt collars appear to be made of celluloid, an early form of plastic. These were popular at this time and were easier to maintain than cotton collars that had to be starched and ironed. Celluloid shirt sleeve cuffs were also available. The fashion of the time shows the length of pants uniformly draped over the shoes, some without cuffs or unfolded. A variety of ties. More about detachable collars here. Even on a warm day no one has removed the collar and opened up the shirt, although a few have rolled up shirtsleeves.

That guy on the far left has such a manly pose, my computer screen grew a mustache.