Go to the part after Ripley decides to blow up the ship, after they destroy Ash (the android), and just after Ripley looks for and finds Jonesy the cat. When Lamburk and Delilah are collecting the cannisters, As Delilah is tossing them on the floor back towards the cart for Lamburk to pick up the camera switches to severale quick shots where Delilah is in front of the racks collecting them,(there is a big light focused on her.)In the 3rd and 4th shots of her plain as day you can see the shadow of the actor in the the alien costume move into and change position for the next shot.

it realy spoils the next scene where the alien attacks and kills Delilah and Lamburk