I saw an advanced screening (post #17) and Doug Jones did a Q & A session afterwards. He's the actor who plays Pan and also the flabby-yet-bony fairy muncher.

Anyways, someone asked him about weird and nasty shit he's had to do (since he's played a lot of creatures, bugs, etc.) And one of the thing's he said was that in the scene where he eats the fairies, he was actually chomping on a condom filled with colored fluid.

He said they really wanted to capture the right elasticity and snap.