In this scene, Lennie and George are sitting around their fire for the night and talking about the house they want to have when they get the money. But George stops in the middle because he knows that they won't accomplish their dreams because Lennie always gets them in trouble. This shows that even from the beginning, George knew it wasn't happening.
Ch. 6 pg. 99
In this scene, George is playing cards. Lennie picks up a face card and sees that "Both ends the same," meaning both ends of the card are the same. But the author words it in a way where it's foreshadowing that he will have the same fate as the dog, who got shot in the back of the head. This clever word play catches us off guard and some don't even notice it.
In this scene, Lennie kills the puppy because he was too rough with it even after George and the others told him to be careful with the newborn pups. This foreshadows the death of Curley's wife because Lennie just can't help himself when it comes to soft things, like the puppy and Curley's wife's hair.
In this scene, a heron catches a snake from the pond and kills it. In the book, the snake symbolizes evil, which would be Lennie. And the heron symbolizes George as he kills Lennie, taking away the 'evil,' as the heron did with the snake.