Question about legal issues at work...?

I am the director of nursing in a nursing home. That means I am second in command, just under the administrator. The other day while the administrator was out of the building, the maintenance man came in my office and chewed me out. He said some really cruel things to me. I felt like he was disciplining me. Note: He and the administrator are drinking buddies and friends outside of work. I called the administrator to talk about what happened, and she said she would call me back and never did. I called my support people at the corporate office to complain, and now they are going to do an investigation. When the administrator finds out I called corporate, can she fire me just to retaliate? I'm on salary. I'm pretty sure I don't have a lot of rights. I live in Arkansas, which is a right to work state. What are my rights?