"The science is wrong in question X."
My experience with physics teachers (high school, college, and university) is that we tend to have some opinions on content and assessment. Strong opinions. And they don't all match.
Given a hundred potential exam items, I wonder how many would gain unanimous approval from attendees of a section meeting of The American Association of Physics Teachers. We're a clever lot, and we can likely poke holes in any test item you put before us, no matter how simple or straightforward you think it is.
All questions on the CST are vetted and field-tested. Items written for the testing contractor are vetted by the contractor, California Department of Education personnel, and the Assessment Review Panel, which is made up of professional scientists and science educators (kindergarten through university). Many questions get burned at one level or another as they make their way to the CST. Some less-than-perfect questions even get included on operation forms. But as far as anyone in the process knows, the questions have solid content and are aligned to standards.
And if I failed to mention it before, releasing a question puts it beyond the reach of future operational forms.