Is there any symbolism in A Farewell to Arms?

YES!  Even though the novels structure and irony is in the
forefront of most critical examination of this novel, it certainly contains symbolism. 
Here are two:

Rain is a frequent symbol in literature and
is often used to foreshadow some type of bad luck or even doom.  It rains when Henry
travels, showing his journey through misfortune.  It rains during the cholera outbreak
and it rains when his fiance and the baby die.  For Henry, rain is perpetual and
symbolizes misfortune and death.

Stars are a symbol of
achievement and status in the military.  They are physical representations of Henry's
pride in himself and his confidence in those around him.  He is pleased and comforted
that his surgeon has several stars on his uniform.  However, he removes his own stars
from his own uniform when he deserts the military.  This removal represents his loss of
pride and confidence in himself and in his own cause.

There
are other examples of symbolism, but these two should get you started and give you
direction as you continue to study the novel.