In episode 3, the gates on the Isle of Wonder are locked, I can't follow the darn checker piece inside, and I can't figure where the hell the key is or how to pry the gate open 
There have been some glitches with episode 3 that we're working on fixing. Start a new episode 3 game without carrying over your episode 2 save; that should fix the issue. The gates aren't supposed to be locked. One you unlock them, they're unlocked. They shouldn't be re-locking on you. Unfortunately, that hasn't stopped the game from doing so. I hope this helps.