How to Handle Mistakes During a Performance
Ignore them. Let go of the mistake and keep going.
Performance for an audience, teacher, camera, or even just a practice performance is obviously not practice. There is no stopping or going back unless something goes very wrong.
Ignore mistakes and keep going. If you’re at a place of practicing performance in preparation for a real performance, be sure to practice moving on from mistakes.
If possible, record yourself for later review. Then take notes about things to improve.
Some mistakes are only mistakes — one off errors due to shaky hands or other factors. Some mistakes, however, are mistakes of intention. Passages or pieces were left to chance and no deliberate choices were made or real practice wasn’t done. Some inconsistent tone is due to adrenaline, but some is because no choice was ever made about how a passage should sound. No interpretation was developed. No fingerings were chosen.
Only the performer can decide if a mistake in a performance was due to a lack of intent or just the result of a genuine flub. Flubs get better with more experience performing. Mistakes of intention get better with deliberate practice.