Backdoor pilots are episodes in shows that serve to introduce spin-off series. Networks will sometimes do this so that they can use the ratings and viewer feedback from the episode to determine whether or not it is worth it to turn the episode into a series. Many of us have probably seen backdoor pilot episodes, but in case you saw one and didn’t know what it was, here are 6 TV episodes that you didn’t know were backdoor pilots:
6. Smallville – Aqua
Smallville’s season five episode “Aqua” was not supposed to be a backdoor pilot for an Aquaman television spinoff; however, as work on the episode progressed, it became clear that the character had potential for his own series. While Aquaman went into production, the show was ultimately not picked up by The CW network, but it was later released on iTunes.
Source: DC Wiki – Wikia