While preforming surgery is it common to make a mistake ?

It's very uncommon, and exceptions are always extremely serious. This is part of why we require medical students to go to medical school for so many years, and why you must be a resident for so long before you may practice. It's also why you must continue learning and recertifying yourself over and over throughout your career. It's also why medical malpractice insurance is so expensive, and part of why doctors must charge such exorbitantly high rates. You can be sure that after years of practice, and dedicated work, you will be competent to perform surgery over and over without error. However, you should remember that it will take significant practice and to be successful you must be willing to do whatever it takes to complete medical school and your residency.