I get an uncaught Security Error in Chrome (looking in the Developer Tools)
Uncaught SecurityError: A history state object with URL 'http://careers.stackoverflow.com/jobs?searchTerm=&pg=2' cannot be created in a document with origin 'https://careers.stackoverflow.com'. jobs.min.js?v=8525c7a8307d:1
(anonymous function) jobs.min.js?v=8525c7a8307d:1
c jquery.js:3048
p.fireWith jquery.js:3160
k jquery.js:8235
r jquery.js:8778
Firefox blocks the content
Blocked loading mixed active content "http://careers.stackoverflow.com/jobs?searchTerm=&pg=2&_=1389866004471"[Learn More]
Careers is being served by https but the pager uses the http which results in the above behavior and errors.
I´m not sure if https is fully supported yet, but when you access Careers using http it works as expected.