Last month I tripped over a dog and fell against one of the closet mirrors, as well. Fortunately, ours has the safety backing (sorry I can't help you there) and I've used painters tape across the two cracks to minimize any more cracking. One thing I am curious about is if anyone has removed one of these mirrors, and where they got a replacement. Mine are glued/epoxied in over small bent metal tabs, and my local Lowes only has mirror ready to cut in 36"X36".
2013 Voltage 3895
2011 Ford F-350 DRW w/ Firestone airbags and heavy duty compressor, Edge Insight CTS, Curt Q24