diff --git a/torchrl/modules/tensordict_module/sequence.py b/torchrl/modules/tensordict_module/sequence.py
index 6ef07b6c93a..7157e174092 100644
--- a/torchrl/modules/tensordict_module/sequence.py
+++ b/torchrl/modules/tensordict_module/sequence.py
@@ -153,7 +153,9 @@ def _compute_in_and_out_keys(self, modules: List[TensorDictModule]) -> Tuple[Lis
             # necessary to run a TensorDictModule. If a key is an intermediary in
             # the chain, there is no reason why it should belong to the input
             # TensorDict.
-            in_keys += [key for key in module.in_keys if key not in out_keys + in_keys]
+            for in_key in module.in_keys:
+                if in_key not in (out_keys + in_keys):
+                    in_keys.append(in_key)
             out_keys += module.out_keys
 
         out_keys = [
@@ -271,12 +273,20 @@ def _run_module(
         if not self.partial_tolerant or all(
             key in tensordict_keys for key in module.in_keys
         ):
-            tensordict = module(tensordict, params=params, buffers=buffers, **kwargs)
+            if params is not None or buffers is not None:
+                tensordict = module(
+                    tensordict, params=params, buffers=buffers, **kwargs
+                )
+            else:
+                tensordict = module(tensordict, **kwargs)
         elif self.partial_tolerant and isinstance(tensordict, LazyStackedTensorDict):
             for sub_td in tensordict.tensordicts:
                 tensordict_keys = set(sub_td.keys())
                 if all(key in tensordict_keys for key in module.in_keys):
-                    module(sub_td, params=params, buffers=buffers, **kwargs)
+                    if params is not None or buffers is not None:
+                        module(sub_td, params=params, buffers=buffers, **kwargs)
+                    else:
+                        module(sub_td, **kwargs)
             tensordict._update_valid_keys()
         return tensordict
 
@@ -348,7 +358,10 @@ def __len__(self):
         return len(self.module)
 
     def __getitem__(self, index: Union[int, slice]) -> TensorDictModule:
-        return self.module.__getitem__(index)
+        if isinstance(index, int):
+            return self.module.__getitem__(index)
+        else:
+            return TensorDictSequential(*self.module.__getitem__(index))
 
     def __setitem__(self, index: int, tensordict_module: TensorDictModule) -> None:
         return self.module.__setitem__(idx=index, module=tensordict_module)