Revealing mistake: In one scene, two of three prisoners get killed by the alien. The last one is sprayed with blood and tries to escape in panic. With his left arm, he leans upon a half-open, hydraulic-powered metal door. However, it moves a little to the left, and as the prisoner takes his hands off, it immediately snaps back to the right. Now even if you suppose that there was no hydraulic pressure behind it, it should not have moved to the right again. It is very obvious that this door is just a light-weighted part of the scenery. (00:43:17)
Revealing mistake: As Ripley and Dillon lure the Alien into the piston chamber, Morse closes them just in time. Watch closely - he misses the switch. (01:38:15)
Answer: Agreed the Queen could have stowed the eggs away on her body as Alien bodies, especially one her size, could easily have a couple of eggs hidden upon her, and we would not know. They are masters of disguise these creatures and can merge in with their own environments or others...what's to say an egg can't look like part of the Queen's body? In addition, could Facehuggers not attach themselves to the Queen's body and merge with it somehow? Flatten themselves against her skin maybe?