I was looking around on YouTube for gummi dragon rescue videos and noticed a very recent video of a strange gummi dragon rescue level that calls for rescuing 2 types of gummi dragons. One of them is the usual ones, but the other one is strangely a gummi dragon with a hazelnut superimposed over them.
https://www.youtube.com/watch?v=o-6Q0h3bwQM
When the hazelnut gummi dragon is rescued and removed from the board, the hazelnut disappears as they break out of the egg, then they suddenly change back to a hazelnut that flies away to the objective window of the HUD.
Could this be a bug? From the looks of this video, it's from the PC version of the game.