Traditional cider makers would lob a sheeps head in to help the fermentation process so I'm told!
While we're on the subject of unexpectedly non-veggie stuff. Here's a list of what I've found...
Gelatine and rennet seem to be the most common bits of unexpected animal.
Wagon Wheels. (Gelatine)
Walkers Cheese and Onion crisps (animal rennet)
Pringles pizza flavour (cochineal)
Sharps Extra-strong mints (Gelatine)
It's late. If I can think of any more I'll post them in the morn.