Do not panic.
Just because you're directing a show that goes on in 3 hours--that you are also stage managing, have costumed, and built sets for ( ohcrapihavetofixthatbackdroptoo!---and ohcrapwheredidthemicrophonegetput? and Ohcrapthepianodied!!!!!!)---doesn't mean that you get to panic.
This show requires magic.
It requires focus.
And a positive attitude.
Rally the troops, get out there, break a leg---It's gonna be FINE!