We lost our not quite 2 year old within an hour of being at our resort-first family Disney trip. DH apparently set him down while we were ordering QS and he wandered off. Thankfully, we found him less than 5 mins later in the attached gift shop at SSR, sitting on the floor looking at Mickey postcards. We asked a couple CMs and they hadn't seen a toddler...
Anyway, best advice is to take a pic of your kid in the morning. A full body pic including their shoes as shoes are something that are likely not going to change in abduction cases. Have your phone number on their clothes, a dog tag on a bracelet, a necklace, shoe tag, temp tattoo- something, that way if someone finds them, they can be reunited with you quicker. If they are old enough to understand, show them how to identify CMs and to identify one if they are lost. Teach them to stay where they are and you or a CM will find them. Teach them not to go with a stranger, and how to know who is safe, and if they ever feel uncomfortable, to scream, cuz worst case scenario, if someone unsavory is trying to get them to go with them, screaming will at least draw attention and hopefully scare them away as well as get the kid help.