Phone interview with a current creative director and then in-person interview with that person and two other team members where we did a portfolio review and regular interview type questions

I applied online and within 24 hours heard back that they'd like to schedule a phone interview with a member of the creative leadership team. I was excited and prepared thoroughly, but the interview ended up being fairly standard. We discussed company structure, leadership style and project management. Most of the conversation was very process focused. Despite this, there were several red flags that crept into the conversation and by the end of the interview, I believe that both the interviewer and myself realized it wasn't a perfect fit. HOWEVER, the thing that turned the interview experience into an unpleasant one I only found out about later. It seems that upon hanging up the phone with me, the interviewer, without my knowledge, permission, or consent, proceeded to reach out to one of the managers at my company for a "quick reference". This ended up putting me in a very uncomfortable spot at work as I had been attempting to keep my job hunt under the radar. This is the most unprofessional thing I have ever experienced during a job interview and I am still extremely upset that it happened.