The one meltdown I recall witnessing was totally understandable (a lost, scared kid) but it was really memorable so I thought I'd share:
'Twas a sunny, hectic early january day in the year of our lord 2011. I, a guest, was chatting with a CM friend at the entrance to the Beauty and the Beast show at HS. Another guest comes up to us (seeing my friend's uniform) and says she thinks there's a little lost boy and points him out. Sure enough, there really is a little kid clearly alone and looking scared walking by. Since he's a little further away and my friend can't really leave her spot, I volunteer to go get the kid. I regret that decision.
I walk up to him, smile and say "Hi there! Are you lost?". The poor kid stands frozen for a second, then shouts "I don't talk to strangers!" and runs past me. Oh ****. But wait! My CM friend sees what's going on and rushes to intercept the guy. She smiles, shows him her CM badge(?) and goes "Hey there! I work for Mickey, are-"
She doesn't get to finish the sentence, because the little boy shouts at the top of his lungs "I.DON'T.TALK.TO.STRANGERS!!!!" and starts bawling and then runs away. Oooh ****. We rush after him but thanks to the crowd we lose him and don't know if he went to the rollercoaster or ToT so we split up. I go to ToT, CM maning the entrance assures me no little boy walked past. Turns out he did run past and the CM didn't see, but we don't know that yet so start getting really worried, wondering if the boy had actually doubled back and run the other way.
After some tense minutes of frantically looking for him and checking to see if there was a parent looking for a kid somewhere, we find out a CM found the boy, now with a brother, at ToT, and was talking to them at the exit, just before/after (I dont recall exactly where) the photo part. When we get there, the little boy is yelling for his mother but rapidly calming down because the CM is soothing him and his also scared looking brother. There is still no news of anyone reporting a lost child, so we're wondering wth when...
From the outside of the ride comes this mother and four other kids all with shirts that match the lost boys, and they go to watch the ride photos. The boys see and run to them. The kid we met first starts yelling "Mummy, mummy where WERE you??" The mother looks at him indifferently and says she'd been outside ToT, and brushes him off. We explain he was found lost near the B&B stage and she goes "Oh, okay, come along [boy]." and walks away totally uncaring despite just finding out her kid had been running around crying through the park. Wow.