I would flush with clean water as soon as possible. Since the components were submerged in mud, it does not matter if they get wet again. Clear water is not much of an issue, its the solids and dissolved impurities that are the problem. The impurities are corrosive and conductive. Whatever you do, don't apply power to "see if it still works" before cleaning. Remove any batteries before wetting.

A while back a customer brought in a receiver that was the victim of a feline induced floating candle spill -- about an ounce of vegetable oil disappeared inside the receiver. The next morning I gently flushed this oil with some acetone and managed to not dissolve anything important. After several years the customer moved out of my area and the receiver was still running.

Soda spills are some of the worst.