diff --git a/crates/polars-core/src/chunked_array/array/iterator.rs b/crates/polars-core/src/chunked_array/array/iterator.rs
index cbb38f954e5e..d17d34e5582b 100644
--- a/crates/polars-core/src/chunked_array/array/iterator.rs
+++ b/crates/polars-core/src/chunked_array/array/iterator.rs
@@ -61,7 +61,7 @@ impl ArrayChunked {
             series_container,
             NonNull::new(ptr).unwrap(),
             self.downcast_iter().flat_map(|arr| arr.iter()),
-            inner_dtype,
+            inner_dtype.clone(),
         )
     }
 
@@ -72,7 +72,7 @@ impl ArrayChunked {
         if self.is_empty() {
             return Ok(Series::new_empty(
                 self.name(),
-                &DataType::List(Box::new(self.inner_dtype())),
+                &DataType::List(Box::new(self.inner_dtype().clone())),
             )
             .list()
             .unwrap()
diff --git a/crates/polars-core/src/chunked_array/array/mod.rs b/crates/polars-core/src/chunked_array/array/mod.rs
index b92255a8f995..96fee06ff3b2 100644
--- a/crates/polars-core/src/chunked_array/array/mod.rs
+++ b/crates/polars-core/src/chunked_array/array/mod.rs
@@ -6,9 +6,9 @@ use crate::prelude::*;
 
 impl ArrayChunked {
     /// Get the inner data type of the fixed size list.
-    pub fn inner_dtype(&self) -> DataType {
+    pub fn inner_dtype(&self) -> &DataType {
         match self.dtype() {
-            DataType::Array(dt, _size) => *dt.clone(),
+            DataType::Array(dt, _size) => dt.as_ref(),
             _ => unreachable!(),
         }
     }
@@ -23,7 +23,7 @@ impl ArrayChunked {
     /// # Safety
     /// The caller must ensure that the logical type given fits the physical type of the array.
     pub unsafe fn to_logical(&mut self, inner_dtype: DataType) {
-        debug_assert_eq!(inner_dtype.to_physical(), self.inner_dtype());
+        debug_assert_eq!(&inner_dtype.to_physical(), self.inner_dtype());
         let width = self.width();
         let fld = Arc::make_mut(&mut self.field);
         fld.coerce(DataType::Array(Box::new(inner_dtype), width))
@@ -34,7 +34,7 @@ impl ArrayChunked {
         let chunks: Vec<_> = self.downcast_iter().map(|c| c.values().clone()).collect();
 
         // SAFETY: Data type of arrays matches because they are chunks from the same array.
-        unsafe { Series::from_chunks_and_dtype_unchecked(self.name(), chunks, &self.inner_dtype()) }
+        unsafe { Series::from_chunks_and_dtype_unchecked(self.name(), chunks, self.inner_dtype()) }
     }
 
     /// Ignore the list indices and apply `func` to the inner type as [`Series`].
diff --git a/crates/polars-core/src/chunked_array/cast.rs b/crates/polars-core/src/chunked_array/cast.rs
index 82ffa79f4af1..b329dc661b1d 100644
--- a/crates/polars-core/src/chunked_array/cast.rs
+++ b/crates/polars-core/src/chunked_array/cast.rs
@@ -412,6 +412,11 @@ impl ChunkCast for ListChunked {
             #[cfg(feature = "dtype-array")]
             Array(child_type, width) => {
                 let physical_type = data_type.to_physical();
+
+                // TODO!: properly implement this recursively.
+                #[cfg(feature = "dtype-categorical")]
+                polars_ensure!(!matches!(&**child_type, Categorical(_, _)), InvalidOperation: "array of categorical is not yet supported");
+
                 // cast to the physical type to avoid logical chunks.
                 let chunks = cast_chunks(self.chunks(), &physical_type, true)?;
                 // SAFETY: we just casted so the dtype matches.
@@ -457,7 +462,7 @@ impl ChunkCast for ArrayChunked {
                 );
 
                 match (self.inner_dtype(), &**child_type) {
-                    (old, new) if old == *new => Ok(self.clone().into_series()),
+                    (old, new) if old == new => Ok(self.clone().into_series()),
                     #[cfg(feature = "dtype-categorical")]
                     (dt, Categorical(None, _) | Enum(_, _)) if !matches!(dt, String) => {
                         polars_bail!(InvalidOperation: "cannot cast Array inner type: '{:?}' to dtype: {:?}", dt, child_type)
@@ -571,7 +576,7 @@ fn cast_fixed_size_list(
     let arr = ca.downcast_iter().next().unwrap();
     // SAFETY: inner dtype is passed correctly
     let s = unsafe {
-        Series::from_chunks_and_dtype_unchecked("", vec![arr.values().clone()], &ca.inner_dtype())
+        Series::from_chunks_and_dtype_unchecked("", vec![arr.values().clone()], ca.inner_dtype())
     };
     let new_inner = s.cast(child_type)?;
 
diff --git a/crates/polars-core/src/chunked_array/iterator/mod.rs b/crates/polars-core/src/chunked_array/iterator/mod.rs
index 27781b892876..1ffacdb4bbb1 100644
--- a/crates/polars-core/src/chunked_array/iterator/mod.rs
+++ b/crates/polars-core/src/chunked_array/iterator/mod.rs
@@ -282,7 +282,7 @@ impl<'a> IntoIterator for &'a ArrayChunked {
                             Some(Series::from_chunks_and_dtype_unchecked(
                                 "",
                                 vec![arr],
-                                &dtype,
+                                dtype,
                             ))
                         }),
                 )
@@ -296,7 +296,7 @@ impl<'a> IntoIterator for &'a ArrayChunked {
                         .trust_my_length(self.len())
                         .map(move |arr| {
                             arr.map(|arr| {
-                                Series::from_chunks_and_dtype_unchecked("", vec![arr], &dtype)
+                                Series::from_chunks_and_dtype_unchecked("", vec![arr], dtype)
                             })
                         }),
                 )
diff --git a/crates/polars-core/src/chunked_array/ops/explode.rs b/crates/polars-core/src/chunked_array/ops/explode.rs
index 735792c19572..ca55ac6836e8 100644
--- a/crates/polars-core/src/chunked_array/ops/explode.rs
+++ b/crates/polars-core/src/chunked_array/ops/explode.rs
@@ -291,7 +291,7 @@ impl ExplodeByOffsets for ArrayChunked {
         let cap = get_capacity(offsets);
         let inner_type = self.inner_dtype();
         let mut builder =
-            get_fixed_size_list_builder(&inner_type, cap, self.width(), self.name()).unwrap();
+            get_fixed_size_list_builder(inner_type, cap, self.width(), self.name()).unwrap();
 
         let mut start = offsets[0] as usize;
         let mut last = start;
diff --git a/crates/polars-core/src/chunked_array/ops/explode_and_offsets.rs b/crates/polars-core/src/chunked_array/ops/explode_and_offsets.rs
index 7c08d4de622a..f407c6245bd8 100644
--- a/crates/polars-core/src/chunked_array/ops/explode_and_offsets.rs
+++ b/crates/polars-core/src/chunked_array/ops/explode_and_offsets.rs
@@ -179,7 +179,7 @@ impl ChunkExplode for ArrayChunked {
         if arr.null_count() == 0 {
             let s = Series::try_from((self.name(), arr.values().clone()))
                 .unwrap()
-                .cast(&ca.inner_dtype())?;
+                .cast(ca.inner_dtype())?;
             let width = self.width() as i64;
             let offsets = (0..self.len() + 1)
                 .map(|i| {
@@ -224,7 +224,7 @@ impl ChunkExplode for ArrayChunked {
         Ok((
             // SAFETY: inner_dtype should be correct
             unsafe {
-                Series::from_chunks_and_dtype_unchecked(ca.name(), vec![chunk], &ca.inner_dtype())
+                Series::from_chunks_and_dtype_unchecked(ca.name(), vec![chunk], ca.inner_dtype())
             },
             offsets,
         ))
diff --git a/crates/polars-core/src/chunked_array/ops/mod.rs b/crates/polars-core/src/chunked_array/ops/mod.rs
index c6f434e97675..30e0f275ab1e 100644
--- a/crates/polars-core/src/chunked_array/ops/mod.rs
+++ b/crates/polars-core/src/chunked_array/ops/mod.rs
@@ -524,13 +524,13 @@ impl ChunkExpandAtIndex<FixedSizeListType> for ArrayChunked {
         match opt_val {
             Some(val) => {
                 let mut ca = ArrayChunked::full(self.name(), &val, length);
-                unsafe { ca.to_logical(self.inner_dtype()) };
+                unsafe { ca.to_logical(self.inner_dtype().clone()) };
                 ca
             },
             None => ArrayChunked::full_null_with_dtype(
                 self.name(),
                 length,
-                &self.inner_dtype(),
+                self.inner_dtype(),
                 self.width(),
             ),
         }
diff --git a/crates/polars-core/src/chunked_array/ops/reverse.rs b/crates/polars-core/src/chunked_array/ops/reverse.rs
index fcc622fe10a3..9d3b0938f390 100644
--- a/crates/polars-core/src/chunked_array/ops/reverse.rs
+++ b/crates/polars-core/src/chunked_array/ops/reverse.rs
@@ -89,7 +89,7 @@ impl ChunkReverse for ArrayChunked {
         let values = arr.values().as_ref();
 
         let mut builder =
-            get_fixed_size_list_builder(&ca.inner_dtype(), ca.len(), ca.width(), ca.name())
+            get_fixed_size_list_builder(ca.inner_dtype(), ca.len(), ca.width(), ca.name())
                 .expect("not yet supported");
 
         // SAFETY, we are within bounds
diff --git a/crates/polars-core/src/chunked_array/ops/shift.rs b/crates/polars-core/src/chunked_array/ops/shift.rs
index ecb64f7b79cd..2938c1ba5ecd 100644
--- a/crates/polars-core/src/chunked_array/ops/shift.rs
+++ b/crates/polars-core/src/chunked_array/ops/shift.rs
@@ -147,7 +147,7 @@ impl ChunkShiftFill<FixedSizeListType, Option<&Series>> for ArrayChunked {
         let mut fill = match fill_value {
             Some(val) => Self::full(self.name(), val, fill_length),
             None => {
-                ArrayChunked::full_null_with_dtype(self.name(), fill_length, &self.inner_dtype(), 0)
+                ArrayChunked::full_null_with_dtype(self.name(), fill_length, self.inner_dtype(), 0)
             },
         };
 
diff --git a/crates/polars-ops/src/chunked_array/array/dispersion.rs b/crates/polars-ops/src/chunked_array/array/dispersion.rs
index e7039ac5db2e..afec05d0f539 100644
--- a/crates/polars-ops/src/chunked_array/array/dispersion.rs
+++ b/crates/polars-ops/src/chunked_array/array/dispersion.rs
@@ -13,7 +13,7 @@ pub(super) fn median_with_nulls(ca: &ArrayChunked) -> PolarsResult<Series> {
             let out: Int64Chunked = ca
                 .apply_amortized_generic(|s| s.and_then(|s| s.as_ref().median().map(|v| v as i64)))
                 .with_name(ca.name());
-            out.into_duration(tu).into_series()
+            out.into_duration(*tu).into_series()
         },
         _ => {
             let out: Float64Chunked = ca
@@ -39,7 +39,7 @@ pub(super) fn std_with_nulls(ca: &ArrayChunked, ddof: u8) -> PolarsResult<Series
             let out: Int64Chunked = ca
                 .apply_amortized_generic(|s| s.and_then(|s| s.as_ref().std(ddof).map(|v| v as i64)))
                 .with_name(ca.name());
-            out.into_duration(tu).into_series()
+            out.into_duration(*tu).into_series()
         },
         _ => {
             let out: Float64Chunked = ca
diff --git a/crates/polars-ops/src/chunked_array/array/get.rs b/crates/polars-ops/src/chunked_array/array/get.rs
index 11d498c396f7..46bf7232e390 100644
--- a/crates/polars-ops/src/chunked_array/array/get.rs
+++ b/crates/polars-ops/src/chunked_array/array/get.rs
@@ -13,7 +13,7 @@ fn array_get_literal(ca: &ArrayChunked, idx: i64, null_on_oob: bool) -> PolarsRe
         .collect::<PolarsResult<Vec<_>>>()?;
     Series::try_from((ca.name(), chunks))
         .unwrap()
-        .cast(&ca.inner_dtype())
+        .cast(ca.inner_dtype())
 }
 
 /// Get the value by literal index in the array.
@@ -31,14 +31,14 @@ pub fn array_get(
             if let Some(index) = index {
                 array_get_literal(ca, index, null_on_oob)
             } else {
-                Ok(Series::full_null(ca.name(), ca.len(), &ca.inner_dtype()))
+                Ok(Series::full_null(ca.name(), ca.len(), ca.inner_dtype()))
             }
         },
         len if len == ca.len() => {
             let out = binary_to_series_arr_get(ca, index, null_on_oob, |arr, idx, nob| {
                 sub_fixed_size_list_get(arr, idx, nob)
             });
-            out?.cast(&ca.inner_dtype())
+            out?.cast(ca.inner_dtype())
         },
         len => polars_bail!(
             ComputeError:
diff --git a/crates/polars-ops/src/chunked_array/array/namespace.rs b/crates/polars-ops/src/chunked_array/array/namespace.rs
index 84381b777f71..1fa813be05a9 100644
--- a/crates/polars-ops/src/chunked_array/array/namespace.rs
+++ b/crates/polars-ops/src/chunked_array/array/namespace.rs
@@ -41,13 +41,13 @@ pub trait ArrayNameSpace: AsArray {
         let ca = self.as_array();
 
         if has_inner_nulls(ca) {
-            return sum_with_nulls(ca, &ca.inner_dtype());
+            return sum_with_nulls(ca, ca.inner_dtype());
         };
 
         match ca.inner_dtype() {
             DataType::Boolean => Ok(count_boolean_bits(ca).into_series()),
-            dt if dt.is_numeric() => Ok(sum_array_numerical(ca, &dt)),
-            dt => sum_with_nulls(ca, &dt),
+            dt if dt.is_numeric() => Ok(sum_array_numerical(ca, dt)),
+            dt => sum_with_nulls(ca, dt),
         }
     }
 
@@ -151,7 +151,7 @@ pub trait ArrayNameSpace: AsArray {
                     ArrayChunked::full_null_with_dtype(
                         ca.name(),
                         ca.len(),
-                        &ca.inner_dtype(),
+                        ca.inner_dtype(),
                         ca.width(),
                     )
                 }
diff --git a/py-polars/tests/unit/test_errors.py b/py-polars/tests/unit/test_errors.py
index e98d9637e88b..91a8e2fe3825 100644
--- a/py-polars/tests/unit/test_errors.py
+++ b/py-polars/tests/unit/test_errors.py
@@ -653,3 +653,8 @@ def test_fill_null_invalid_supertype() -> None:
         pl.InvalidOperationError, match="could not determine supertype of"
     ):
         df.select(pl.col("date").fill_null(1.0))
+
+
+def test_raise_array_of_cats() -> None:
+    with pytest.raises(pl.InvalidOperationError, match="is not yet supported"):
+        pl.Series([["a", "b"], ["a", "c"]], dtype=pl.Array(pl.Categorical, 2))
diff --git a/py-polars/tests/unit/testing/test_assert_series_equal.py b/py-polars/tests/unit/testing/test_assert_series_equal.py
index d04766edfb95..bf6812b1f241 100644
--- a/py-polars/tests/unit/testing/test_assert_series_equal.py
+++ b/py-polars/tests/unit/testing/test_assert_series_equal.py
@@ -673,12 +673,6 @@ def test_assert_series_equal_nested_categorical_as_str_global() -> None:
     "s",
     [
         pl.Series([["a", "b"], ["a"]], dtype=pl.List(pl.Categorical)),
-        pytest.param(
-            pl.Series([["a", "b"], ["a", "c"]], dtype=pl.Array(pl.Categorical, 2)),
-            marks=pytest.mark.xfail(
-                reason="Currently bugged: https://github.com/pola-rs/polars/issues/16706"
-            ),
-        ),
         pl.Series([{"a": "x"}, {"a": "y"}], dtype=pl.Struct({"a": pl.Categorical})),
     ],
 )