It looks like all URLs in plain text on the page are being rewritten (eg. from Amazon.com to Amazon.com.prx.uk.teleport.to). URLs in <a href="..."> fields are not, but only if they point off the domain you're visiting.
It's certainly not the intended behavior, but it's not a surprising bug either. The rewrite was surprisingly tough to make work even most of the time. But if you could share the specific site this happened on, I will likely be able to fix it.