“Can we fly six of the chorus girls during the 2nd act opening number?”
Directors always have crazy ideas. That particular idea took a week of design work, rigging, and rehearsal to pull off. The one technical detail you need to know is that the key safety issue was properly balancing the rigs while the dancers got on and off the playground swings they were sitting on.
The rig was balanced for two dancers, one on either side of the stage. When they were both on the swings, a stage hand could raise them 15 feet in the air with one hand. Before getting off the swings, we had to replace their weight with sandbags clipped to the rigs offstage. That kept the system safely in balance. We had rehearsed the switch multiple times; it was a complex piece of offstage choreography in its own right involving nine stage hands and six dancers.
Opening night, the scene runs smoothly, the curtain comes down, and one of the dancers hops off her swing early before the sandbags have been clipped on. As her counterpart starts what is about to be a very rapid ascent into the rafters, I see Mark, the stagehand at the rail controlling the rig, reach up about two feet, grab the ropes, and use his bodyweight as a temporary counterweight. The sandbags were clipped on, dancer number 2 came safely back to the ground, and the show went on without interruption. My heart restarted several minutes later.
The audience saw none of this. The director delivered his moment of magic. The crew got a story to talk about at the cast party.
Most people seem content to simply enjoy the magic. I find the magic more compelling when I understand how it is made. Making magic takes work; the more you understand of the work, the better the magic you can make.
We live in a world that appears magical. But it has been built by designers and engineers and carpenters and stagehands. If you leave the magic to the experts you are bound by their imaginations. If you are prepared to come backstage and invest in learning something about how the magic is done, then you can become another collaborator in imagining and creating new magic.