The next day, I got a text about the other key I left in the park. The finder said they had left them by a bathroom, and after some picture messaging, I managed to find the correct bathroom. However, after searching for an hour and texting back and forth with the finder (who was super helpful, by the way), I concluded that somebody else must have taken the key for whatever reason.

As for the key at the bus stop, it took a few days, but I eventually got a text saying that it was still there waiting for me. But when I got there, I found a mangled keychain with the QR code peeled open and the key gone.

As for the others, the QR code could have gotten wrecked or the keys kicked into a bush or down a drain. Here are some tips for those of you who want to make your own:

The verdict? It's an awesome idea and I suggest doing it, but definitely add your phone number to the back for non-smartphone users.