Incorrect redirect after commenting

Actually, it looks like a problem being caused by the ReCAPTCHA plugin. Have you tried turning that plugin off?

CAPTCHAs are generally ineffective for comments anyway. They prevent spam to some degree, but they prevent real-people even more, and are terrible for accessibility.

A better way to fight spam is to use plugins that don’t require human inputs. I personally use a combination of Simple Trackback Validation, Cookies for Comments, and Akismet. These work great and don’t block real-people as well as spambots.