“What can we do to prevent 'show stopping' issues relating to the increasingly technical aspect of modern theatre?” - basically a “How to I plan for the worst, even though I hope for the best?” discussion.
Wherever possible we run real-time backups. We do a big musical every summer, and last summer ran backing tracks from Sound Cue System for the first time (previously they have always been run off hard drive systems). The operator, the MD and myself were all
slightly nervous about this, as backing tracks tend to be fairly critical, and SCS is Windows-based...while we use SCS daily, and very rarely have trouble, the stakes were much higher on the musical! We decided early on that we needed to have a second SCS computer running in case of the primary falling over, and given that it is keyboard-fired, built a trigger switch which was wired into two keyboards so that one press would trigger both computers, meaning they'd be running the backing tracks in parallel. Each computer ran into its own M-Audio box, and then the outputs from those ran through a crash-box so that if the primary computer fell over, the op would hit the crash-box switch and the backup would then go live. Happily, in 12 weeks (something like 80 shows) we never had to use the backup, but it was a major weight off everybody's shoulders knowing it was there! In terms of lighting, we have a permanent backup desk in the DMX stream - sometime once the plot is complete, the operator stores the scenes in the backup desk. It's had to be used only once as far as I know, when the 520 died (and needed a complete rebuild...) but again, it's the peace of mind factor coming into play.
The whole director-refusing-to-acknowledge-Plan-B thing scares me a little; I don't know that I'd discuss plan B with the cast anyway, but I'd certainly talk it through with my crew and have something in place for myself. I did have an episode where my leading lady's sister was dying of cancer; the director said to me "if her sister dies we will have to give her compassionate leave, therefore I've asked **** (another actress) to be on standby. She knows the play because she's been in it before, so just be prepared for that, but keep it quiet." I said I was happy to know that there was a Plan B in place, but that I'd need to let Wardrobe know just in case, as the two actresses were very, very different sizes and there was no way that the costume would fit the understudy - and it was
The Country Wife, so not exactly a play where you could just find a replacement costume in the theatre's stock! The director was horrified when I said that, saying "no, no, no, you can't mention it to anybody, you needed to know but nobody else does." I couldn't let that one go - didn't argue any further with the director (because I'd be beating my head against a brick wall) but I took it to the production manager, my direct boss, and left it in his capable hands. Fortunately the situation didn't arise, because I still am not sure what we would have done...