Krane is back and he has succeeded in turning the entire adult population of New York into kids and the kids into adults. Only bionic humans are immune. It is up to Chase and Maya to restore their families and everyone else to normal before it's too late. But it requires finding Krane's hiding spot to reverse it, and that isn't easy.
- The title and premise are references to William Brent and Ariel Winter's film, Opposite Day.
- Chase references this by saying to Tina, "I feel like we've been through all this before". Technically, however, he could have also been referring to becoming kids in Prodigious.
- Bionic humans are immune to powerful personality-swapping scientific spells.
- This is a birthday episode for Duggie Davenport.