Well, I'm hoping there will be an egg transformation scene and something would be inferred about it being different to what happened to the rest. The observing character could comment about how it's situated in a more protected place or it might even be X-Rayed or autopsied and what's shown on the monitor is, to us, obviously an embryonic Queen, complete with the crest (they should probably have retained the same puppets), but the character's would never know that.
It doesn't have to be 'rescued' and could easily be accidentally destroyed in some way, but those are some ways of achieving that, in a story.