In my case, a CD is added to the kits on a (just in case) basis.

I am a city boy ( a 55+ y/o boy for that matter ) and not close to any kind of danger in which I may need a signalling mirror. So , no , I haven't used or bought a real signalling mirror, nor do I know where it can be sold in my part of the world.

In the old days, I used to go in a ship for 10 days as part of my work, or 1-2 days in nearby deserts , but nothing more serious. Now with age and added family responsibilities, I am limited to work in a six-floor corporate building, where i don't see much use for a signalling mirror. A whistle, however, is a part of every kit I have.

Also, my travels are limited to well-travelled highways either by car or as a passenger in a bus ..etc.