my $root = { some_object => obj };
$root->{some_object} = new Object;
my $arrayref = $root->{some_object}->objectMethodReturningEmbeddedArrayref();
$arrayref->[0] = 5;
{
  local $arrayref->[0] = 0;
  # execute some code, which sees 0 not 5
}

# now array element is 5 again