This scene shows when Carlson carelessly killed Candy's dog. And it shows the characterization of Carlson. This shows that he is heartless or emotionless. Because he kills the dog like nothing and comes back and cleans the gun in front of Candy.
In this scene it shows how George is surrounded by others but still would rather do stuff himself. And doesn't like being alone.
Simile: "A water snake slipped along on the pool, its head held uplike a little periscope."