Forgive me if this has been brought up either here or meta.se before, but I could not find it in either.
On a user's activity page, beneath their reputation, there is a label that says "top x% overall". Clicking this brings you to the user reputation leagues. However, there appears to be a flaw here.
At the top of this page, it shows a cumulative total of users (as seen in the image below).
Lower down, in the right-hand area, there is a table representing a breakdown of the number of users by reputation total, as shown below.
Adding the values in the second column, we arrive at the same number listed in the first image; that is to say, each row represents the total number of users with at least that reputation but less than the prior row's total.
This is confirmed by looking at the breakdowns; there are in fact 67 users here with >50,000 rep. However, if these data are cumulative, then the bottom-most row, representing users with 1+ reputation, should read the same as the number in the first image. It does not. Furthermore, it does not appear to be exclusive of the cumulative total in the 200+ rep row. Instead, it appears to incorrectly subtract the values of all prior rows, instead of just the cumulative 200+ row. (This detail was pointed out by @quid; thank you!)