I think that most people, even those who know the quotation (which probably isn't most, especially not kids), wouldn't make the connection until the last scene anyway. And even if someone DOES see what's coming, so what? They wouldn't know HOW ZigZag would be betrayed, so it would still be a surprise and something to watch for. And in any case, this is beating a dead horse... but I do wonder why the name was changed. "Phido" is funny, true, but not quite so appropriate.