I also faced the same issue anywhere in that level, and yes, I also had unlocked the rockets (I played the levels at the same order I was finding them in my way :) ). I'm really glad you could reproduce it and fix it!
there is also a glitch i found where when you enter the giant egg, the the boss music starts playing, it only plays the first note then it stops until it says either go to the main menu or back to game.
