Max items allowed to be added in a Release, in a single instance via API, is 25.
The update release items option doesn't add the new references added to an updated version of a release item automatically. Manual addition is required.
The update release items option doesn't update the entries with newer in-progress versions.
A rollback release cannot be scheduled and must be deployed manually.
A release must be deployed before it can be rolled back. You cannot roll back a release that has not been deployed, including a scheduled release before its scheduled date.
After you delete a rollback release, you must redeploy the original release before creating another rollback release.