Facts
It's usually forgivable to make a minor mistake or two during the driving test. Minor errors mean mistakes that do not affect road safety or your own safety. For example, if you forget to turn the signal out of a roundabout, this may be okay, unless it happens several times or in connection with other mistakes.
Whether you pass or not is up to the driving examiner, who makes an overall assessment of your driving. So if everything else went well except for a mistake or two, you can still pass. But if several small mistakes occur, it can be enough to get a failing grade.