Remarque's passionately anti-war novel about the senseless slaughter of World War I and the young men who were its victims is punctuated with lyrical, poetic language, some of it almost Shakespearean in tone. Examples of metaphors, which are comparisons that don't use the words "like" or "as," follow: 

I am young, I am twenty years old; yet I know nothing of life but despair, death, fear, and fatuous superficiality cast over an abyss of sorrow.

"Abyss of sorrow" is a metaphor for the war, and is particularly apt, for the men spend much of their time in trenches, which are pits (comparable, symbolically, to abysses) in the ground.  

The narrator also uses metaphor when he likens the lives of the young men in the trenches to "little flames." He compares the war that threatens these flames (the soldiers) to a "storm," and we can visualize it as a mighty, windy, whirling rain downpour threatening to put out these vulnerable flames. This metaphor emphasizes the power of war in contrast to the vulnerability of the soldiers:

We are little flames poorly sheltered by frail walls against the storm of dissolution and madness, in which we flicker and sometimes almost go out . . .

The narrator also says:

Our thoughts are clay, they are moulded with the changes of the days . . .

We can visualize their thoughts, an abstract concept, a ball of clay, a concrete object, but endlessly malleable.

As for similes, which are comparisons using "like" or "as," we learn that:

Kantorek had been our schoolmaster, a stern little man in a grey tailcoat, with a face like a shrew mouse.

A face like a shrew mouse gives us an image of Kantorek as the petty dictator he is, his small-mindedness compared to a small creature like a mouse.

Remarque has been called "a man who can bend language to his will," for while some of the narrative reads like a journal of the young soldier, Paul Baumer, there are also impressionistic passages with unbalanced, fragmented syntax. The use of figurative language in these passages is frequent.  After the men are in the heat of battle where  “To no man does the earth mean so much as to the soldier," the trucks pick up the men. Then, in Chapter Five, the men learn that their detested officer, Himmelstoss is returning, 

Haie gazes thoughfully at his great paws and winks at me.  The thrashing was the high water mark of his life. [metaphors]

One day the men decide to catch a goose. Paul grabs two; as the geese struggle, Paul describes the action,

In the dark these white patches are terrifying.  My arms have grown wings and I'm almost afraid of going up into the sky, as though I held a couple of captive balloons in my fists.  [metaphor and simile]

As they cook the geese, Paul poetically describes Kat and himself,

We are two men, two minute sparks of life; outside is the night and the circle of death.  We sit on the edge of it crouching in danger, the grease drips from our hands, in our hearts we are close to one another, and the hour is like the room:  flecked over with the lights and shadows of our feelings cast by a quiet fire. [metaphor, metaphor, simile, metaphor]

Further, Paul describes his friend's loss of his humanity as he is now "a little soldier" who has never possessed some sights:

A little soldier and a clear voice, and if anyone were to caress him he would hardly understand, this soldier with the big boots and the shut heart, who marches because he is wearing big boots, and has forgotten all else but marching....Kat stands before me, his gigantic, stooping shadow falls upon me, like home.  [metaphor, simile]

The last line of Chapter Five contains a simile with alliteration:

The outlines of the huts are upon us in the dawn like a dark, deep sleep.