The link for sports site on SO is not working here on http://stackexchange.com/leagues.
Other sites such as Stack Overflow are working it is displaying an error.
It says it is a server fault.
May be a bug therefore i have thought to report it here on meta.
UPDATE: 27th May 2013
As spotted by Daniel Daranas the links for reputation league sports site
the only problem is with the http://stackexchange.com/leagues/189/week/sports
UPDATE: 07th June 2013
All the links for sports site are working now but as spotted by Daniel Daranas there were other few links which were also broken. All of them have been fixed by now except for SmugMug, where the following links are broken:
Its been so long the links are not working for the week page and for month page I just spotted in on June 4th.
UPDATE: 18th June 2013
We have finally come to the conclusion (see comments to the answer below) that a link to a Reputation League gives a 404 error if nobody has scored any reputation. This happened in Smugmug in the last few weeks, until yesterday someone scored some reputation. Suddenly, the Smugmug weekly and monthly reputation league links are not broken anymore, but if from the weekly league you go to the previous week ( http://stackexchange.com/leagues/183/week/smugmug/2013-06-09 ), that's another story: nobody scored any reputation during that week, so the link fails.
I updated the title to convey this conclusion.