Trac Code Comments Plugin
The problem is two-fold. When reviewing code, it's difficult to associate your comments with their appropriate context. Then, collecting all of these new issues into actionable tickets requires a lot of manual effort.
This plugin allows you to leave comments on top of files, changesets, and attachments. Once you've added all of your comments, you can send them to tickets. These include links to these comments and their description.
If you found a bug, create a new issue on github.