In the Star Trek universe, the Prime Directive prohibits Starfleet personnel from interfering with the internal development of alien civilizations. They violate the directive over and over, but even worse, they interfere constantly with the space-time continuum. You can’t really blame the Enterprise crew, or even the writers, because time travel makes for wonderful stories. But it does mess up the continuity of several TV series and a dozen feature films. The Deep Space Nine episode “Trials And Tribble-Ations” even had the DS9 crew interacting with the characters in the 1960s series!
Plenty of Trek episodes dealt with time travel before DS9, but “Trials And Tribble-Ations” is the first to show characters traveling back to the events of a previous series; in a way, it serves as a prototype for the direction the new movie franchise would take, dipping in to the nostalgia of the original series while still maintaining its own voice. The plot here is largely an excuse to let the crew of DS9 interact with some of their “heroes,” as the episode uses footage from the classic original-series entry “The Trouble With Tribbles” intermixed with matching footage from the present. The effect is hugely entertaining, allowing the show to both mock and pay homage to the flaws and wonders of its predecessor. As a bonus, “Trials” also introduces the Department Of Temporal Investigations, a group dedicated to maintaining the internal logic of history. They mostly serve as a framing story, but the existence of the department is a helpful reminder that time travel and the shenanigans that result from it are an integral part of the franchise.
The A.V. Club counts 14 other instances that time travel threw the Star Trek universe off-kilter. They always manage to “set things right” by the end, but who knows what changes they made in their timeline that the characters will never realize?
(Image credit: Nick Wanserski)