Upon digging in, I was appalled that fully 1/3 of the images contained errors or omissions! Some are small (eg a part of a car on the edge of the frame or a ways in the distance not being labeled) but some are egregious (like the woman in the crosswalk with a baby stroller).
I think this really calls out the importance of rigorously inspecting any data you plan to use with your models. Garbage in, garbage out... and self-driving cars should be treated seriously.
I went ahead and corrected by hand the missing bounding boxes and fixed a bunch of other errors like phantom annotations and duplicated boxes. There are still quite a few duplicate boxes (especially around traffic lights) that would have been tedious to fix manually, but if there's enough demand I'll go back and clean those as well.