That is a good teaching moment for ALL of us! Mine are only going to be one year & I've already researched those leash backpacks. Your kids are probably too old for those.
I was lost at Disneyland while there with my uncle's family (sans mom) when I was about 5 as well. Because my mom had so thoroughly explained what to do, within a few minutes of realizing that I could not find my family with the throngs of people everywhere, I walked myself up to a security guard & explained that I was lost. I spent the next 45 minutes in the Disneyland safe daycare for lost kids (yes, they have this).

My mom also always wore a bright red coat if we went to crowded public places so that we could see her easily. She stood out like a sore thumb & probably was always hot, but we never lost track of her that way.

When I was in kindergarten we also started having a secret password someone had to give us if ever they tried to say that they had to pick us up from school in an emergency instead of my mom. She would rehearse the password with us & it was something no one else would know unless they had instructions from her. She did of course also tell us never to approach a stranger's car & to back away if one stopped on the side of the road. I had a great mom & hope to implement her safety ideas.

GGB Triplets Born 32 weeks Nov,2010

Janet