diff --git a/compliance/test_utils.py b/compliance/test_utils.py
index 5308e719bf..40bf0e6202 100644
--- a/compliance/test_utils.py
+++ b/compliance/test_utils.py
@@ -33,6 +33,7 @@ def mock_cybersource_wsdl(mocked_responses, settings, service_version=SERVICE_VE
     Mocks the responses to achieve a functional WSDL
     """
     # in order for zeep to load the wsdl, it will load the wsdl and the accompanying xsd definitions
+    # Note: open() defaults to read mode ("r")
     with open(f"{DATA_DIR}/CyberSourceTransaction_{service_version}.wsdl") as wsdl:  # noqa: PTH123
         mocked_responses.add(
             mocked_responses.GET,
diff --git a/courses/serializers_test.py b/courses/serializers_test.py
index 5bfb0e0a3a..57597e518b 100644
--- a/courses/serializers_test.py
+++ b/courses/serializers_test.py
@@ -6,7 +6,6 @@
 
 import factory
 import pytest
-import pytz
 from django.contrib.auth.models import AnonymousUser
 
 from cms.constants import FORMAT_ONLINE, FORMAT_OTHER
@@ -107,7 +106,7 @@ def test_serialize_program(  # noqa: PLR0913
 
     non_live_run = CourseRunFactory.create(
         course=course1,
-        end_date=datetime.max.replace(tzinfo=pytz.utc),
+        end_date=datetime.max.replace(tzinfo=timezone.utc),
         expiration_date=None,
         live=False,
     )
diff --git a/courses/views_test.py b/courses/views_test.py
index 87d65d4df3..7cb16e424f 100644
--- a/courses/views_test.py
+++ b/courses/views_test.py
@@ -282,6 +282,7 @@ def test_course_view(  # noqa: PLR0913
             url = reverse("user-dashboard")
             class_name = "enrolled"
 
+    # Note: UTF-8 is the default encoding in Python 3.
     assert (
         f'<a class="enroll-button {class_name}" href="{url}">'.encode() in resp.content
     ) is has_button
@@ -346,6 +347,7 @@ def test_program_view(  # noqa: PLR0913
             url = reverse("user-dashboard")
             class_name = "enrolled"
 
+    # Note: UTF-8 is the default encoding in Python 3.
     assert (
         f'<a class="enroll-button {class_name}" href="{url}">'.encode() in resp.content
     ) is has_button
diff --git a/ecommerce/management/commands/invalidate_payment_coupons.py b/ecommerce/management/commands/invalidate_payment_coupons.py
index 9df911933d..3af1101340 100644
--- a/ecommerce/management/commands/invalidate_payment_coupons.py
+++ b/ecommerce/management/commands/invalidate_payment_coupons.py
@@ -61,6 +61,7 @@ def handle(self, *args, **kwargs):  # noqa: ARG002
             codes = Coupon.objects.filter(enabled=True, payment=payment).all()
         else:
             try:
+                # Note: open() defaults to read mode ("r")
                 with open(kwargs["codefile"]) as file:  # noqa: PTH123
                     procCodes = [line.strip() for line in file]
             except Exception as e:  # noqa: BLE001
diff --git a/mitxpro/test_utils.py b/mitxpro/test_utils.py
index 3e894c3722..447d6d4653 100644
--- a/mitxpro/test_utils.py
+++ b/mitxpro/test_utils.py
@@ -170,6 +170,7 @@ def create_tempfile_csv(rows_iter):
         writer = csv.writer(f, delimiter=",")
         for row in rows_iter:
             writer.writerow(row)
+    # Note: open() defaults to read mode ("r")
     with open(f.name) as user_csv:  # noqa: PTH123
         return SimpleUploadedFile(
             f.name, user_csv.read().encode("utf8"), content_type="application/csv"