Another tip about kids getting lost - some of mine are too young to memorize our cell number so I wrote it on their arm. Sure it looked like my 2 yr old had a tattoo, but I felt better. The info was visible and didn't have to be searched for like putting it somewhere on their clothing would have been.
I use the Disney Luggage tags that they send with your documents for this. I attached the tags to my children using strong keyrings attached to their back beltloop. I put my husbands cell phone number on them and instruct them to find a Cast Member if they are lost and show them the tag. They are only 6 and 4, I don't know if they would be able to remember the phone number.
Thankfully, we have never had to use them.
We lost our son, who is now 6 at Chef Mickey's 2 years ago. He was very proud of himself upon his return...he just went for a little walk!