Linking to a trackback, as opposed to just displaying the URL in some textual fashion round about the comments section of a post, is a bit of a problem in WordPress. This is because it doesn’t really take you anywhere, at least not in the way one tends to expect, if you follow the link. The point of a trackback URL is to—and hopefully this is obvious—send a trackback “ping” from somewhere else, preferably another blog. Doing anything else with it is like banging on a door with no house attached, and as far as WordPress is concerned this is a pretty stupid thing to do. So if you visit a trackback URL from a WordPress blog, WordPress assumes you’re more interested in the post it derives from, and redirects you to it.
This isn’t for the timid or code shy, but his documentation is really clear. If you want to make trackback links work for you, check it out.