The documentation for searching on references notes the following restriction:
You can only search on references on fields which link to a single entry. Fields which hold references to many entries or fields with references to assets are not supported.
To work around this we can fetch all entries, then filter by references within our application, but this is inefficient and precludes pagination.
Given this limitation, this knowledgebase article is misleading. It would be reasonable assumption that a Movie content type would allow multiple Actor references. However, the example provided would only work with a single-reference actors field.
Are there plans to remove this limitation in a future version?