So the mistake is not a major bug, the contributions of the paper remain the same, but still, I feel it was a silly statistical error. Can I correct it, even if the reviewers missed catching it?
While the answer by markvs already tells you the right course of action, I think the following addendum is important:
The phrase "even if the reviewers missed catching it" indicates that you might have an inaccurate impression of the peer review process and should maybe change your perspective on it:
As an important part of scientific quality ensurance, peer review serves several purposes. One purpose is to decrease the probability that a published paper contains errors. It is not a guarantee that a published paper does not contain any errors.
It is not among the purposes of peer review to partially relieve the authors of their responsibility for the correctness of their results. If your readers find a mistake in your paper, they will blame you for it, not the reviewers.
Given these two points, it is clear that you should take all necessary measures to make your paper as correct as you possibly can, also if the reviewers overlooked a mistake.
Important note. If you make non-trivial changes after the completion of the peer review process, I strongly recommend to inform the handling editor of these changes - the editor then has the opportunity to approve (or, sometimes maybe, disapprove) the changes; and if they think that the changes are also in need of peer review, they then also have the opportunity to send the revised file to the reviewers once again. (EDIT: As pointed out by Danica in a comment, in some fields and for some publication venues this last paragraph does not apply.)
It is your responsibility to ensure that the text is correct.
It is not the responsibility of the reviewers. The reviewers only act as gatekeepers to offer an expert opinion and state that the paper looks to be correct and interesting. They will not check every detail (necessarily) and will likely not see small mistakes and errors.
The Question isn't really clear but if, from another perspective, you're Asking whether the fact that there are reviewers absolves you of responsibility for accuracy then no; of course it never could.
When I worked in publishing everyone, at every level, knew that if anyone - specifically including the telephone sanitisers - questioned anything, the correct procedure was to amend the wording of that thing.
Of course right there and then, I could give the sanitiser an explanation, and so what?
What explanation could I give to 50-100,000 readers, after publication?