Recently my paper was accepted with major revisions, and while following the reviewers' comments and revising my paper, I realized that both reviewers missed a mistake that I did in a function block diagram. What should I do?

 1. Correct it and let them know in the joined point-by-point response?
 2. Wait until they tell me about it? 
 3. Ask them to double check that diagram?

I'm afraid it may send the wrong message and I'd look disrespectful by showing them that they missed the mistake!