Hi All,
New member here - morgoth0. I used to be a part of AVPOutbreak back in the day but I've been away for quite a while... too long...

I have to say though that it's great to see so many of the people I remember from those days are still around. I hope to be around for a while too so long as you don't mind.
Anywhoo, a few hours after I found this site something came to me that I'd never considered before when discussing the mystery of how the egg arrived on the Sulaco - the egg that gave birth to two face-huggers, heinous allegations about the android Bishop, mysterious reincarnations of Hudson or Burke, Queen teleportation never seen before or Super-Facehuggers and many other weird and wonderful theories

Back in the day I tried like hell to rationalize the end of Aliens with the beginning of Alien
3 and I've seen that others have continued to do so but from what I could see from searches here and on google no one so far has come up with this idea (maybe they did and it was shot down, in which case I apologize for bringing it up again).
Anyway, my theory is that rather than bringing an egg or a couple of facehuggers, rather than an act of treachery from Bishop (which also would have been difficult to accomplish within the timeline), the Queen brought on board a chestburster - the infant form of the Xenomorph... volia:
Note: I want to make it clear that in this explanation I am not relying on an accelerated development rate for the implantation to chest-bursting as in AvP. I suggested explanations for why that could still be considered canon a long time ago and my argument means that the Aliens on LV426 would develop at the same rates as in the original Alien movie. 
The idea of chestbusters being present on LV426 at the time of the destruction of Weyland-Yutani's colony is not out of the question. After all, a live colonist was found by the Marines at the time the chestburster bursted forth. All it would take is one other colonist to have been implanted soon after that one for this theory to not be immediately discounted. That unfortunate colonist would presumably have been further into the nest and not found by the Colonial Marines who were by then otherwise engaged

Now, we also can assume that any Alien can become a Queen. That question has never really been resolved (but then again the entire lifecycle of the Xenomorph has never really been canonically resolved has it?) but as far as I can see a theory that the Xenomorph will become a Queen if there is no other Queen present fits in the canon. The assumption here is that should no other Queen be present, a Xenomorph will "metamorphosis" into a Queen and thus be able to lay eggs... can you see where I'm going here?

Okay so here's the only thing you have to assume and accept for this theory to be possible as far as I can see it (and please feel free to shoot it down if you see flaws): that there was a chestburster either in the egg chamber or found by the Queen on her pursuit of Ripley to the freight elevators. The footage of the Queen at the elevator and beyond do not discount this, an immature Xenomorph can be small and would blend in with the Queen's body.
So she grabbed a chestburster - makes more sense than grabbing facehuggers since it would, in a couple of days be pretty capable of both defending/serving her and continuing the line if she should die (by virtue of laying lots of eggs). She then escaped LV426 on the dropship.
On arrival on the Sulaco several things could have happened: (1) she immediately released the chestburster which slithered through a ventilator or access hatch and hid, or it could have remained hidden in the guts of the dropship, emerging during Ripley's battle with the Queen and escaping during the confusion; or (3) it remained hidden in the dropship until everything quitened down. The last is unlikely since I'd assume that Ripley would check the dropship for bugs and the first seems the likeliest since it would have been tough (but not impossible) for the chestburster to avoid being sucked out of the cargo lock.
NOTE: The sound at the end of the movie could have been a chestburster moving rather than a facehugger...
The Xenomorph matures while the remaining crew sleeps. Not knowing what it faces, but knowing that they killed its Queen, the chestburster sets up her egg chamber in a place unlikely to be found - perhaps "a service or maintenance corridor below the main deck, and against the hull" (thanks Deelzelboy)


After laying eggs plenty of them (in order to ensure that she's prepared for the future), in fact so may that she has to lay eggs on the celling given the small size of the space available, she goes hunting for her prey. Finally finding them in the hypersleep chamber she goes and fetches three facehuggers.
This is the only flaw I've seen so far: normally the drones bring eggs to their victims rather than facehuggers. Maybe it's because she's a Queen or maybe it's because the nest hadn't been established throughout the ship yet she behaves differently.After that things progress as in the opening sequence of Alien
3. Ripley is infected, a facehugger travels down with Newt and all seems to be explained... Have I missed anything?

I'm sure I probably have

Cheers,
Grahame.