I don't think it's a "specialty" but I love to have a Dirty Bombay Sapphire Martini up at Victoria Falls. As for dinner, I adore an Fairview African Pinotage (red wine) with dinner.
As mentioned, Victoria Falls Mist is popular. I had a few Safari Martinis (vodka, with a bit of tangerine and cranberry) when I dined at Boma. They were good, but almost too sweet for a martini