I agree with most of the PP comments. As a nurse educator, I absolutely cannot understand anyone being terminated for a mistake in a skills lab. That's actually the place where you are expected to make mistakes.... and learn from them. That's the purpose of a skills lab or other simulation experience. Duh. There's got to be more to this story, I can't believe that any HR department would let this happen.
I do not agree with the PP who said that previous jobs do not show up in background checks. Yes, they do. If you were paid & FICA/taxes were deducted, then this job will show up when they run a full background check as required by US Federal requirements for health care employees. This information is associated with your SSN# which serves as our basic 'people identifier' in the US.