I agree with jfrick. EVERYONE can tell that you're missing notes if you look like you're not having fun. Even though it was original material and they couldn't have possibly known the RIGHT notes. And be sure not to LOOK when someone else in the band makes a mistake, THEN it's obvious. If you look comfortable and keep on after mistakes giving the "nope, couldn't have been me, I don't make mistakes" look then the crowd will listen to the performance for what it is, Eruption, an awesome cover! SMILE AND JUMP AROUND!!