Widescreen sets first appeared in the early 90's. A few anamorphic LD's were sold with them. None were sold by themselves, AFAIK. Most titles came out in Japan only and are called "squeeze" Laserdiscs. Some European players could send a signal to a properly equipped widescreen set to unsquish it's picture. As Pioneer used similar parts across it's product lines, you can find a "16:9" LED hidden in the display panels of some U.S. models.
AC3 and DTS Laserdiscs were on the market at least three years before DVD even hit the shelves. It's a pity we never got a version of the Hi-Def stuff over here.