Knife Trick
We watch as Bishop expertly does a knife trick on Hudson's hand. It is a symbol that he is more than human in his ability to coordinate at such a speed that is far beyond the capabilities of a human being and leads to us knowing that he is a robot.
Jars
When the Marine crew comes into the colony, they find jars that contain the alien species, with one still alive. The is a symbol that they have been studying the species and desire to manipulate it for their own use rather than destroy it.
Red
We see the Marine crew covered in red light as the aliens converge upon them. The red lighting is a symbol that death is upon these people and prepares the audience for more blood shed.
Cocoons
The marines come across a woman who is still alive but cocooned by an alien. This is a symbol that the aliens intent is to completely take over humanity.
Shuttle
The shuttle crashes and burns when the alien kills the pilot attempting to pick up Ripley and the crew. This is a symbol that there is very little hope now as the next evac ship will take 17 days to arrive.
