Running 1.38a + security + FEC:

If javascript is disabled, so the error-checking falls within the server's realm, none of the input errors are displayed for the "Write a Review" page. The culprit appears to be \includes\modules\pages\product_reviews_write\header.php, starting at line 56:
Code:
  if (strlen($review_text) < REVIEW_TEXT_MIN_LENGTH) {
    $error = true;

    $messageStack->add('review_text', JS_REVIEW_TEXT);
  }

  if (($rating < 1) || ($rating > 5)) {
    $error = true;

    $messageStack->add('review_text', JS_REVIEW_RATING);
  }
Which should be:
Code:
  if (strlen($review_text) < REVIEW_TEXT_MIN_LENGTH) {
    $error = true;

    $messageStack->add('product_reviews_write', JS_REVIEW_TEXT);
  }

  if (($rating < 1) || ($rating > 5)) {
    $error = true;

    $messageStack->add('product_reviews_write', JS_REVIEW_RATING);
  }