10 More Changes That Star Trek Hoped You Wouldn't Notice

10. Starfleet Was The UESPA

There was no mention of Starfleet in the early episodes of The Original Series. Prior to the first mention of Starfleet in the episode Court Martial, the Enterprise was said to be operated by the UESPA (United Earth Space Probe Agency). For decades, it was assumed that the UESPA and Starfleet were the same organisations, and the name change was a single retcon.

After Court Martial, the UESPA wasn't mentioned again for decades, until the Voyager episode Friendship One, which featured an earth probe by the name Friendship 1, with the registry UESPA-1 on its hull. This officially confirmed that the UESPA is still part of canon (even as far back as 2067, when Friendship 1 was launched). The registry, UESPA-1, also seemed to imply that this was the first vessel developed by the agency. The UESPA has also been referenced in more subtle ways throughout the franchise, like by appearing on dedication plaques on the Star Trek: Enterprise and Generations sets.

Today, it's assumed that the UESPA was in charge of coordinating the Enterprise's five-year mission from The Original Series, while the crew themselves included members of both Starfleet and the UESPA (as well as enlisted personnel, like McCoy). This could explain why Kirk chose to report to the UESPA headquarters in Charlie X, rather than Starfleet.

Much like the old look of the Klingons, the Enterprise working with the UESPA is actually canon, despite the fact that we know both changes started as retcons.