I noticed in Review that the progress line graph has a color and a line that don't match up, and then when you get the mouseover, neither lines up with the color on that progress bar:
Can we get an exact explanation of what this is telling us?
The bottom graph shows how close you are to the next badge, which is 250 for reviewer.
Once you have your Reviewer badge the line will still be there on the top graph.
Bar on the first line indicates the next milestone in review specific badges:
The line on the stats bar indicates the next milestone that a user could achieve in earning a review specific badge.
Below screenshot taken from my stats indicates that if I review
Hovering mouse over the stats indicates the details on how much I have achieved with respect to the milestone.