You just established that you are capable of making mistakes, because you just made one. Which creates the opportunity for you to establish that you correct your mistakes swiftly and decisively :)
Simply notify the people involved that the advice you originally gave was wrong, give them the corrected advice and follow up to make sure that they have received your corrected advice and that you are answering any questions relating to the correct advice.
Ideally, you should give a quick run down as to why your original advice was wrong and why your corrected advice is right. I have had the tables turned on me when the recipients of my advice determined from the reasons I gave that my original advice was right, and my corrected advice was wrong :)
Of course, you should create a work environment where your subordinates are not shy about pointing out your mistakes, even in front of your group. I am not enthusiastic about subordinates pointing out my heavy duty mistakes in front of my top management and of course, pointing out my mistakes in front of the customer is, dire emergency situations excepted, a no-no.