not secret stuff per-say, but more like Sea World magic - it's happened to us twice. I will preface this by saying that both of these stories happened years before the park changed hands to the current owners;
When my son was 6, he was TOTALLY into penguins. We would have done the penguin encounter experience with him but he was too young - he was that into it. one morning it's just me and the two kids and we get to the park first thing. We immediately head straight for the penguins and spent some time watching the outdoor Magellin penguins when we spot a trainer with a cat travel carrier come out the side door. I ask my son what he thinks is in the box and he sheepishly says he thinks it's a penguin. The trainer overhears us and says, "That's right, it is a penguin." She takes a couple of steps away from the exhibit, then turns to us and says, "You can join me if you want."
WHAT!?!
I gather up the kids and we follow the trainer over the entrance to the banquet room. She let the penguin out and my son got to help train him! We fed him, and gave him some commands. It was a younger Magellin penguin and she needed to work with him so he would come when the fed him. They do health checks on the penguins during feeding so its really important that each penguin knows what to do. IT WAS AWESOME!
Years later, we go back to Sea World and now my daughter is TOTALLY into Sea Otters. We went to the exhibit WELL before feeding and my daughter is really taking it all in and talking to the trainers. My daughter asked what was in the building behind the exhibit and the trainer invited us in. Not only that, but she took us back to the tank behind the exhibit and let my daughter feed the otters. It meant everything to her - the trainer had no idea.
You hear people talk about Disney Magic, well, there's some Sea World magic for you, and it happened to us twice. I sincerely doubt you'd get either of these experiences like we did - the new owners have turned the very same otter experience into an $80 per person upcharge in fact. All the same, you never know - if you happen by a friendly trainer and have a real interest in the animals who knows? We certainly didn't expect it.