From Nowhere
We watch as the Marines attempt to find the alien lifeform aboard the ship and even with infrared they can't see where the enemy is coming. The imagery shows movement from the aliens in darkness that creates a feeling of suspense in the audience as we are game to what the Marines can't see coming.
Red
The crew is being approached by a massive wave of aliens on Hudson's thermal reader. The entire scene is lit with red light. The imagery creates the feeling that death is coming upon the crew in a major way. And the aliens attack the crew from above and kill Hudson.
Knife trick
Hudson asks Bishop to do a knife trick and he obliges him by playing the knife game on him. The imagery of Bishop cutting through the air so fast creates a tremendous amount of tension that the audience can feel as they wait for the blade to cut through Hudson's hand...which it does note because Bishop is an Artificial Person.
Colony
We see the Marine crew land on the colony. The imagery we see is stark as the colony has been over run by the aliens and there aren't any human beings left alive. The environment is dark, wet and filled by cocoons left by the aliens. It creates the feeling of walking into a haunted house for the audience.
