Well, I (like many others, I should imagine) have come across a fair number of "howlers" in my time ... but don't recall any "visited by others" situations quite as bad as that one.
Hopefully, any catastrophic outcomes were avoided by alert theatre staff.
Anyway ... the lesson to be learned there (and it's a basic one) must be:- "always check your work". As well as making sure that the equipment works correctly (not to mention safely) before returning it to the user.
