If you're talking about KOTR 98, the fall through the cage was totally unplanned, as was the chair falling onto his face. I thought that was pretty common knowledge by now.
No, that's a myth. The only part of that that was unplanned was when the chair hit him in the face.
What! Mick himself says that cage wasn't supposed to give way in his book and on the latest DVD.
I'm pretty sure he didn't say that in his book. In the book, he said that when he and Terry were discussing what he could do in the match, Terry gave him the the idea to be thrown off of the cell, climb back to the top, and get thrown off again as a joke. But, Mick told him "I think I could do it.". If the second fall was an accident, then what was the plan? Were they just going to climb back down and get in the ring? That would have been kind of anticlimactic.