Mercury rules communication and things related to the mind. A job interview may experience different forms of misunderstandings related to communication, writings and documents of any sort. Things may not be fully communicated to one another, or not communicated properly. This can involve agreements and the role that is to be pertained in one's position of employment, and what kind of rights you have.
Mercury rules writing materials and legal documents. Be very careful if you sign any contracts during Mercury retrograde if you get the job. Go through the documents carefully. Take your time and re-read your contract to make sure everything is clear on your end as well as your employer's.