This is in Southern California, by the way.

No way to know without going to the department and asking. Every place is different.

Inspections have steps, some of which require open walls. Do you have pictures of the plumbing and electrical work behind the walls that you can show them? If not, now isn't really the time to find out they need to see in the walls. I'd leave it be, but do it properly onward.

Thanks for the responses. My concern is that the bathroom remodel will be discovered when the inspector comes for any future projects. As I said, the houses in my neighborhood are pretty cookie cutter and many are identical. The new layout will be noticed as the inspector walks past the bathroom to inspect any newly-permitted work.

I don't have pictures.

As long as your permit covers work in progress, not likely to be an issue.

There is no way to know what can happen. Different inspectors in different offices have different tolerances for those who haven't complied. If they've had a bad day---or a good day----or the previous person was a jerk....there's no telling.

Your best bet is to be as nice as you can, and try to make up for all of the a-hole builders that they deal with. "I'm sorry, I didn't know, but now I want to make it right. Help me figure out how to do that. What is your suggestion here?" Respect and being humble go a long way towards gaining good will.

Adding to that, I agree about being nice, offer a cup of coffee, etc. but certainly don't bring up the bathroom unless it were to become an issue for them. If you were to mention it, you've put them in a bad position needlessly. Better they don't know to begin with (even if they do notice and say nothing). And if it were to come up, such as "nice bathroom, when did you get that", don't spill the beans unless you must. Just be pleasant.

I'd just keep the bathroom door closed whenever inspector
shows for the rest of the remodel.

more to the point...why were permits not pulled in
the first place for the bathroom remodel??

best of luck.

I agree with Energy Rater LA. Keep the bathroom door closed. Some people do this all the time anyway. Draw permits on any work in the future. If the bathroom remodel is discovered and the inspector insists on inspecting it at that time, fine. Respectfully do whatever you need to do at that time. If you need to pay a fine, pay; tear out work, do it.

The difference between coming clean now and going in to the building department, admitting the error, and doing whatever they demand now and what I suggest above is:
1. Inspector may not see or care about the bathroom when in to inspect future work. In that case, you saved the trouble and cost of fessing up on your own.
2. If you have to tear the bathroom out in either instance, at least you are doing it later if you don't fess up. You got more "use" out of your materials and you get to replace those materials with ones that are more modern and in the "style" of at least a few years later if you wait for the inspector to find it.