[nichos44]

Those false positives are because fmri runs countless statistical tests and the earlier "misconfigured software" wasn't running stringent enough multiple comparisons corrections. Basically the same issue in the classic "jelly bean causes acne" xkcd (https://xkcd.com/882/). The exact number depends on voxel size, temporal resolution, and experimental condition but is somewhere close to tens of thousands of tests.

The "images" that are presented in fMRI studies and that contain false positives are representing results of statistical tests (t-values, and f-values after correction) not the contents of voxels. So the false positive rate of an fMRI has very little to do with the accuracy of a voxel's content in a structural MRI.