Kristin's injury wasn't because of the hair toss, that just agrivated it.
But, as people have said, thats live theatre.
In the Lion King, Heather Headly (as Nala) broke her ankle during a performance. Her understudy was on vacation and the second understudy was out sick. An ensemble member went on as Nala but had to hold a script for the rest of the performance. An understudy was on as the giraffe, he took a misstep and fell and was rushed to the hospital. Someone was on the wrong mark when the back of the stage rose and she fell and had to be taken to the hospital. There have been a bunch of other injuries too, these are just off the top of my head.
And just remember Christina Applegate, she broke her foot TWIRLING AROUND A POLE, not doing anything particularly difficult or dangerous.
Whatever happened to class?