So maybe you said something you thought was true because perhaps your heard it from someone you trusted, or perhaps you put two and two together and forgot about some other variable, and then mentioned it on the internet....
And then someone calls you out on it, possibly with proof.
Step 1. Do not look at this as an opportunity to continue to defend your position.
Step 2. Try to have a sense of humor.
Step 3. Try to realize that, deep down, you know you were wrong
Step 4. Swallow Ego.
Step 5. Admit it. Say "Oops" or something. It won't hurt that much.
(and please don't bother with the cockamamie excuses like "my dog ate my brain cells" or "I was too busy doing intervals to think clearly" or whatever)