Anyone who remembers the hoary old ROH Wagner production in which a stuffed bird slid along a wire hung 3m above the stage - stuttering and jamming along the way - will remember why they tell you never to work with children or animals (even stuffed ones). In any case, Production will have come along by this time to tell you that you have already used 90% of your entire Ring budget on the special effect by which Alberich turns into a toad, and you now have fourpence to dress and decorate the remaining three parts of the Tetralogy... woodpeckers are out. You can have Penguin costume from the animals in The Magic Flute, or you can have Papagena, but let them know before the tea-break because the soprano's a heck of a size and it will need letting-out....
I do remember the WNO
Parsifal in which, to mark the shooting of the swan, what looked like a rubber chicken was dropped unceremoniously from the flies, landing on-stage with a loud plop, to the ill-disguised amusement of quite a lot of the chorus ...
And while on the subject of WNO, I once managed to see their
Siegfried and
Magic Flute within a few days of one another - the dragon that chased Tamino on stage was quite clearly the same one that had served as Fafner the previous week.