Complex sentence: The first appearance of The Stainless Steel Rat in prog 140 was supposed to be preceded with a brief panel of explanation of who Jim was, however an editorial error meant that the panel actually appeared at the end of the first episode, not the beginning.
Split into simpler sentences: The first appearance of The Stainless Steel Rat in prog 140 was supposed to be preceded with a brief panel of explanation of who Jim was. However, an editorial error meant that the panel actually appeared at the end of the first episode, not the beginning.