diff --git a/gymnasium/spaces/oneof.py b/gymnasium/spaces/oneof.py
index d88f0b130..be158e614 100644
--- a/gymnasium/spaces/oneof.py
+++ b/gymnasium/spaces/oneof.py
@@ -43,6 +43,7 @@ class OneOf(Space[Any]):
             spaces (Iterable[Space]): The spaces that are involved in the cartesian product.
             seed: Optionally, you can use this argument to seed the RNGs of the ``spaces`` to ensure reproducible sampling.
         """
+        assert isinstance(spaces, Iterable), f"{spaces} is not an iterable"
         self.spaces = tuple(spaces)
         assert len(self.spaces) > 0, "Empty `OneOf` spaces are not supported."
         for space in self.spaces:
@@ -105,7 +106,7 @@ class OneOf(Space[Any]):
         Returns:
             Tuple of the subspace's samples
         """
-        subspace_idx = int(self.np_random.integers(0, len(self.spaces)))
+        subspace_idx = self.np_random.integers(0, len(self.spaces), dtype=np.int64)
         subspace = self.spaces[subspace_idx]
         if mask is not None:
             assert isinstance(
@@ -121,9 +122,14 @@ class OneOf(Space[Any]):
 
     def contains(self, x: tuple[int, Any]) -> bool:
         """Return boolean specifying if x is a valid member of this space."""
-        (idx, value) = x
-
-        return isinstance(x, tuple) and self.spaces[idx].contains(value)
+        # subspace_idx, subspace_value = x
+        return (
+            isinstance(x, tuple)
+            and len(x) == 2
+            and isinstance(x[0], (np.int64, int))
+            and 0 <= x[0] < len(self.spaces)
+            and self.spaces[x[0]].contains(x[1])
+        )
 
     def __repr__(self) -> str:
         """Gives a string representation of this space."""
@@ -141,7 +147,10 @@ class OneOf(Space[Any]):
     def from_jsonable(self, sample_n: list[list[Any]]) -> list[tuple[Any, ...]]:
         """Convert a JSONable data type to a batch of samples from this space."""
         return [
-            (space_idx, self.spaces[space_idx].from_jsonable([jsonable_sample])[0])
+            (
+                np.int64(space_idx),
+                self.spaces[space_idx].from_jsonable([jsonable_sample])[0],
+            )
             for space_idx, jsonable_sample in sample_n
         ]
 
diff --git a/gymnasium/spaces/utils.py b/gymnasium/spaces/utils.py
index 8f737af28..ed53ca566 100644
--- a/gymnasium/spaces/utils.py
+++ b/gymnasium/spaces/utils.py
@@ -421,7 +421,7 @@ def _unflatten_sequence(space: Sequence, x: tuple[Any, ...]) -> tuple[Any, ...]
 
 @unflatten.register(OneOf)
 def _unflatten_oneof(space: OneOf, x: NDArray[Any]) -> tuple[int, Any]:
-    idx = int(x[0])
+    idx = np.int64(x[0])
     sub_space = space.spaces[idx]
 
     original_size = flatdim(sub_space)
diff --git a/gymnasium/vector/utils/shared_memory.py b/gymnasium/vector/utils/shared_memory.py
index e30444862..66494718c 100644
--- a/gymnasium/vector/utils/shared_memory.py
+++ b/gymnasium/vector/utils/shared_memory.py
@@ -93,14 +93,16 @@ def _create_text_shared_memory(space: Text, n: int = 1, ctx=mp):
 
 @create_shared_memory.register(OneOf)
 def _create_oneof_shared_memory(space: OneOf, n: int = 1, ctx=mp):
-    return (ctx.Array(np.int32, n),) + _create_tuple_shared_memory(space)
+    return (ctx.Array(np.dtype(np.int64).char, n),) + tuple(
+        create_shared_memory(subspace, n=n, ctx=ctx) for subspace in space.spaces
+    )
 
 
 @create_shared_memory.register(Graph)
 @create_shared_memory.register(Sequence)
 def _create_dynamic_shared_memory(space: Graph | Sequence, n: int = 1, ctx=mp):
     raise TypeError(
-        f"As {space} has a dynamic shape then it is not possible to make a static shared memory."
+        f"As {space} has a dynamic shape so its not possible to make a static shared memory."
     )
 
 
@@ -193,14 +195,15 @@ def _read_text_from_shared_memory(
 def _read_one_of_from_shared_memory(
     space: OneOf, shared_memory, n: int = 1
 ) -> tuple[Any, ...]:
-    sample_indexes = np.frombuffer(shared_memory[0].get_obj(), dtype=space.dtype)
+    sample_indexes = np.frombuffer(shared_memory[0].get_obj(), dtype=np.int64)
+
     subspace_samples = tuple(
         read_from_shared_memory(subspace, memory, n=n)
         for (memory, subspace) in zip(shared_memory[1:], space.spaces)
     )
     return tuple(
-        (index, sample[index])
-        for index, sample in zip(sample_indexes, subspace_samples)
+        (sample_index, subspace_samples[sample_index][index])
+        for index, sample_index in enumerate(sample_indexes)
     )
 
 
@@ -279,10 +282,14 @@ def _write_text_to_shared_memory(space: Text, index: int, values: str, shared_me
 
 @write_to_shared_memory.register(OneOf)
 def _write_oneof_to_shared_memory(
-    space: OneOf, index: int, values: tuple[Any, ...], shared_memory
+    space: OneOf, index: int, values: tuple[int, Any], shared_memory
 ):
-    destination = np.frombuffer(shared_memory[0].get_obj(), dtype=np.int32)
-    np.copyto(destination[index : index + 1], values[0])
+    subspace_idx, space_value = values
 
-    for value, memory, subspace in zip(values[1], shared_memory[1:], space.spaces):
-        write_to_shared_memory(subspace, index, value, memory)
+    destination = np.frombuffer(shared_memory[0].get_obj(), dtype=np.int64)
+    np.copyto(destination[index : index + 1], subspace_idx)
+
+    # only the subspace's memory is updated with the sample value, ignoring the other memories as data might not match
+    write_to_shared_memory(
+        space.spaces[subspace_idx], index, space_value, shared_memory[1 + subspace_idx]
+    )
diff --git a/tests/envs/mujoco/test_mujoco_v5.py b/tests/envs/mujoco/test_mujoco_v5.py
index 44ba9a6b2..02149b360 100644
--- a/tests/envs/mujoco/test_mujoco_v5.py
+++ b/tests/envs/mujoco/test_mujoco_v5.py
@@ -436,7 +436,7 @@ def test_observation_structure(env_name: str, version: str):
     env = gym.make(f"{env_name}-{version}").unwrapped
     assert isinstance(env, MujocoEnv)
     if not hasattr(env, "observation_structure"):
-        return
+        pytest.skip("Environment doesn't have an `observation_structure` attribute")
 
     obs_struct = env.observation_structure
 
diff --git a/tests/envs/test_action_dim_check.py b/tests/envs/test_action_dim_check.py
index afe230e09..d42ad0eb7 100644
--- a/tests/envs/test_action_dim_check.py
+++ b/tests/envs/test_action_dim_check.py
@@ -71,7 +71,8 @@ def test_discrete_actions_out_of_bound(env: gym.Env):
         env (gym.Env): the gymnasium environment
     """
     if env.metadata.get("jax", False):
-        return
+        assert env.spec is not None
+        pytest.skip(f"Skipping jax-based environment ({env.spec.id})")
 
     assert isinstance(env.action_space, spaces.Discrete)
     upper_bound = env.action_space.start + env.action_space.n - 1
@@ -106,7 +107,8 @@ def test_box_actions_out_of_bound(env: gym.Env):
         env (gym.Env): the gymnasium environment
     """
     if env.metadata.get("jax", False):
-        return
+        assert env.spec is not None
+        pytest.skip(f"Skipping jax-based environment ({env.spec.id})")
 
     env.reset(seed=42)
 
diff --git a/tests/envs/test_envs.py b/tests/envs/test_envs.py
index f6b48b135..0855871a0 100644
--- a/tests/envs/test_envs.py
+++ b/tests/envs/test_envs.py
@@ -63,7 +63,7 @@ def test_all_env_passive_env_checker(spec):
 
     for warning in caught_warnings:
         if not passive_check_pattern.search(str(warning.message)):
-            print(f"Unexpected warning: {warning.message}")
+            raise ValueError(f"Unexpected warning: {warning.message}")
 
 
 # Note that this precludes running this test in multiple threads.
@@ -90,7 +90,7 @@ def test_env_determinism_rollout(env_spec: EnvSpec):
     """
     # Don't check rollout equality if it's a nondeterministic environment.
     if env_spec.nondeterministic is True:
-        return
+        pytest.skip(f"Skipping {env_spec.id} as it is non-deterministic")
 
     env_1 = env_spec.make(disable_env_checker=True)
     env_2 = env_spec.make(disable_env_checker=True)
diff --git a/tests/spaces/test_oneof.py b/tests/spaces/test_oneof.py
index 61088768f..f4a879bf9 100644
--- a/tests/spaces/test_oneof.py
+++ b/tests/spaces/test_oneof.py
@@ -62,6 +62,10 @@ def test_oneof_contains():
     assert (0, np.array([0.5], dtype=np.float32)) in space
     assert (1, np.array([-0.5, -0.5], dtype=np.float32)) in space
 
+    assert (np.int64(0), np.array([0.5], dtype=np.float32)) in space
+
+    assert (np.int32(0), np.array([0.5], dtype=np.float32)) not in space
+
 
 def test_bad_oneof_seed():
     space = OneOf([Box(0, 1), Box(0, 1)])
diff --git a/tests/test_core.py b/tests/test_core.py
index a91d3d6a7..374bf4bb9 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -118,7 +118,7 @@ def test_example_wrapper(example_env):
             "Can't access `_np_random` of a wrapper, use `.unwrapped._np_random` or `.np_random`."
         ),
     ):
-        print(wrapper_env.access_hidden_np_random())
+        _ = wrapper_env.access_hidden_np_random()
 
 
 class ExampleRewardWrapper(RewardWrapper):
diff --git a/tests/vector/utils/test_shared_memory.py b/tests/vector/utils/test_shared_memory.py
index 9b3118c64..3edf6a45d 100644
--- a/tests/vector/utils/test_shared_memory.py
+++ b/tests/vector/utils/test_shared_memory.py
@@ -33,8 +33,12 @@ def test_shared_memory_create_read_write(space, num, ctx):
 
     try:
         shared_memory = create_shared_memory(space, n=num, ctx=ctx)
-    except TypeError:
-        return
+    except TypeError as err:
+        assert (
+            "has a dynamic shape so its not possible to make a static shared memory."
+            in str(err)
+        )
+        pytest.skip("Skipping space with dynamic shape")
 
     for i, sample in enumerate(samples):
         write_to_shared_memory(space, i, sample, shared_memory)
diff --git a/tests/wrappers/test_jax_to_torch.py b/tests/wrappers/test_jax_to_torch.py
index ef2af4900..54e52e5be 100644
--- a/tests/wrappers/test_jax_to_torch.py
+++ b/tests/wrappers/test_jax_to_torch.py
@@ -96,9 +96,6 @@ class ExampleNamedTuple(NamedTuple):
 )
 def test_roundtripping(value, expected_value):
     """We test numpy -> jax -> numpy as this is direction in the NumpyToJax wrapper."""
-    print(f"{value=}")
-    print(f"{torch_to_jax(value)=}")
-    print(f"{jax_to_torch(torch_to_jax(value))=}")
     roundtripped_value = jax_to_torch(torch_to_jax(value))
     assert torch_data_equivalence(roundtripped_value, expected_value)