If you're a Trekkie, but not a fan of Deep Space Nine, you owe it yourself to watch DS9's fifth season episode, "Trials and Tribble-ations".
If you have a casual familiarity with Star Trek, particularly the original series, you owe it yourself to watch DS9's fifth season episode, "Trials and Tribble-ations".
Scratch all of the above. Just go watch DS9's fifth season episode, "Trials and Tribble-ations".
This episode was produced in celebration of Star Trek's 30th anniversary, and it paid tribute to the original series by adding the DS9 crew to the classic TOS episode "The Trouble with Tribbles".
This could have been an epic disaster. It could have come off as a tacky attempt to mix DS9 with the original series. Instead, it is a masterfully done episode full of comedic moments and tributes to the original series.
If you haven't seen the episode, I won't spoil too much here.
Obviously, in order for the DS9 crew to interact with the original crew, time travel needed to be involved. The writers were clearly aware that time travel had already been overused throughout Trek, and they had some fun with concept. The episode opens with Sisco receiving a visit from Starfleet's "Temporal Investigations" department".
The real fun begins when we get to see the crew interact with TOS characters, props, and sets. The plot fits neatly within the story of the original "Trouble with Tribbles" episode and is packed with comedy geared toward Trek fans.
The DS9 crew does not recognize the Klingons of the original series era. Worf simply responds by saying that they do not discuss the difference in appearance with outsiders.
Dax, who has lived many lifetimes, recalls the era with a sense of nostalgia. She also refers to an affair that one of her previous hosts had with a young Leonard McCoy before he was a doctor ("he had the hands of a surgeon").
An attractive woman flirts with Dr. Bashir. After realizing that this woman has the same name as his great-grandmother, he becomes a bit obsessed with the idea that he might be his own great-grandfather - and that, if he doesn't meet up with her, he may never be born. This is obviously not true; it's not a pre-destination paradox (Temporal Investigations hates those).
I won't go any further because, as I said above, you need to watch the episode. If you haven't seen "The Trouble with Tribbles" from TOS, it might not be a bad idea to watch that first - but it's not required to enjoy and appreciate DS9's "Trials and Tribble-ations". Both episodes are on Netflix, Amazon Prime, and Hulu.