I was fired because I made a mistake and the senior operate for made the same mistake and he was not wrote up or anything.

You can be terminated for any reason or no reason as long as the reason for your termination does not violate a law. In addition, you can be treated differently than another similarly situated employee unless the reason you were treated differently violates a law, such as discrimination based upon age (older worker treated less favorably), gender, pregnancy, disability, race, religion, national origin, color, etc. You may want to consult with an employment attorney if that is the case.   Ohio employment attorney www.mcoffmanlegal.com