Duck is not linked to Austria's National Holiday. Perhaps you mistake duck for goose which is served traditionally in November, known as "Martini Gansl" (St. Martin's goose). This is to commemorate St. Martin who not only divided his coat with a beggar but was elected bishop of Tours against his will. He was hiding in a barn but the geese gabbled and he was found and declared bishop. At least according to the legend...

Pardon me if I am incorrect. But when I was deciding on what to order, I distinctly remember the waiter telling me that was the "special" for the National Day, 26 October. Perhaps he was just trying to sell me on the idea. It doesn't matter insofar as the meal went. It was a memorable one. I now have the motivation to return to Vienna (in November) in a quest for goose.

Platzman, must have been the famous Wiener Schmäh (the Viennese way of being charming, often with a twist). Whenever you want to return to Vienna, feel welcome!