http://www.perlmonks.org?node_id=595273


in reply to WWW::Mechanize fetch differs from firefox browser result (was Re: WWW::Mechanize or WWW::Selenium with javascript redirect)
in thread WWW::Mechanize or WWW::Selenium with javascript redirect

If the site is actually sending different content to Firefox, it must be using the User-Agent string. Just set your User-Agent in Mech to be the same as the one Firefox sends.