I had to look up what exactly Joan McCracken's "illness" was, only to find out that it was Type 1 diabetes.
Boy, they really talked around that, didn't they? You wouldn't have a clue based on the vague way they alluded to some mysterious sickness that causes her an inability to walk at random times? What?
I'm sorry, I'm a Type 1 diabetic myself and I cannot stand it when it's obvious that something has no idea how to portray symptoms of this condition or even what they look like. I know it was a lot harder to treat back then (especially Type 1, it would have been awful), but insulin existed, so she must have been using that at least. With no ability to check blood sugar levels though (or account for food with insulin probably), most likely she would have had fainting spells due to sudden lows- but symptoms of highs are constant thirst and urination, which is less visible.
I'm not sure what that incident was supposed to be portraying in the rehearsal room, where just all of a sudden she's crying and can't walk. It reminded me of that part in Steel Magnolias, where Julia Roberts is perfectly fine and then all of a sudden has a fit and is screaming and throwing things at people until her mom feeds her orange juice against her will.
Umm, what? Do people really not have any clue what low blood sugar looks like? If you don't faint straight out, you feel faint but you know that you need to eat or drink something (with sugar in it) fast. You're not mentally incapacitated. How do people not know this still?