Breaking the contract

Sorry to those that saw this in another section (new to the site and think this is a much better place for this post.)

I am a new graduate joining a hospital for my first job. As a condition of my hire and for a bonus, I am to sign a two year contract that mentions no consequences to breaking the agreement except for forfeiture of my bonus. Of course I intend to stay for more than a year but am probably going to leave the hospital after about a year and a half for various reasons including desires for travel, volunteering and travel nursing opportunities. The money doesn't worry me too much but unwritten consequences do.

Does anyone know of any unspoken consequences to breaking a contract such as bad references, other hospitals or agencies "looking down" on you or other?
Thanks