Frankie, don't worry about your post somehow inspiring terrorists, psychos, or malcontents. I think you are smart to prepare for this sort of threat, and this is a perfect forum to post your questions.

In addition to your whistle, light, and handkerchief, I would seriously suggest a blade of some sort (if legal.) A multi-tool would be a good idea IMO; maybe a smaller one like the Leatherman Juice that can be discreetly carried in your pocket would work for you. I'm not a big believer in carrying bandaids and the like, but I see some merit in some sort of trauma pad if practicable. About 20' of 550# paracord (maybe used as shoelaces?) could come in handy.

I'm not familiar with Montreal's subway system, so obviously I can't advise you about evacuation. But you are already light years ahead of most people if you mark the exits and take the time to read the posted instructions.

Good luck. It seems we are truly all in this together.

Regards, Vince