"Lennie you gonna be sick like you was last night."
Candy's dog shot Chapter 3&4 pg.49
"If you want me to, I'll put the old devil out of his misery right now and get it over with."
Death of Curly's Wife Chapter 5 pg. 91
"Let go, Let go!"
In this scene Lennie and George had just got off the highway and found a spot they would stay at for the night. Eventually it would be easy to realize that this seen was foreshadowing the future. This would be the first time we would see George continuously tell Lennie what to do or not to do, for example he made Lennie stop drinking the water so he wouldn't be sick again. Therefor we can see not everything works as planned or wanted.
Lennie's Death Chapter 6 pg.106
"You.... an' me. Ever'bod gonna be nice to you. Ain't be no more trouble."
Carlson shot Candy's dog in this seen because his dog was useless and suffering. Again, this is foreshadowing the future of Lennie since he is causing suffering and and would suffer more if the people from the ranch found him. After all we can see that sometimes the right choice is the hard one.
In this dramatic scene Lennie breaks Curly's wife's neck after killing a puppy all by accident. Once again this foreshadows that Lennie will mess up his plans with George to own their own little place once they get enough money. In conclusion this scene shows us that no matter how hard someone may try it is hard for people to change.
During this tragic seen George shot Lennie to end his suffering and prevent him for what will happen if the others from the ranch find him. Lennie getting shot in the head by George symbolizes a dream dying or being failed. The idea of this is that not everything in life will work out .