diff --git a/test/test_env.py b/test/test_env.py
index 36671db8922..5fd2f5c60c3 100644
--- a/test/test_env.py
+++ b/test/test_env.py
@@ -1727,7 +1727,7 @@ def test_multi_purpose_env(self, serial):
             env = SerialEnv(2, ContinuousActionVecMockEnv)
         else:
             env = ContinuousActionVecMockEnv()
-        rollout = env.rollout(10)
+        env.rollout(10)
         assert env._step_mdp.validate(None)
         c = SyncDataCollector(
             env, env.rand_action, frames_per_batch=10, total_frames=20
@@ -1736,7 +1736,18 @@ def test_multi_purpose_env(self, serial):
             pass
         assert ("collector", "traj_ids") in data.keys(True)
         assert env._step_mdp.validate(None)
-        rollout = env.rollout(10)
+        env.rollout(10)
+
+        # An exception will be raised when the collector sees extra keys
+        if serial:
+            env = SerialEnv(2, ContinuousActionVecMockEnv)
+        else:
+            env = ContinuousActionVecMockEnv()
+        c = SyncDataCollector(
+            env, env.rand_action, frames_per_batch=10, total_frames=20
+        )
+        for data in c:  # noqa: B007
+            pass
 
 
 @pytest.mark.parametrize("device", get_default_devices())
diff --git a/torchrl/envs/utils.py b/torchrl/envs/utils.py
index 12d282cc86d..6094ccf9f77 100644
--- a/torchrl/envs/utils.py
+++ b/torchrl/envs/utils.py
@@ -167,7 +167,7 @@ def validate(self, tensordict):
             )
             actual = set(tensordict.keys(True, True))
             expected = set(expected)
-            self.validated = expected.union(actual) == expected
+            self.validated = expected.intersection(actual) == expected
             if not self.validated:
                 warnings.warn(
                     "The expected key set and actual key set differ. "