Whenever you are going to be communicating with a mass of people, no matter the medium you plan to use, make sure you have at least one other person proofread your copy. All of your copy, even the subject line.
This email would have made a much larger impact and probably sold more tickets for the show Peter Pan had the subject line been correct. However, I bet their open rate went through the roof to find out who Peter Oan is. :)
Have a great weekend!