Most of these are copied from my answers to this post: https://www.trekbbs.com/threads/did...too-insulting-condescending-about-tos.294716/
I've added a few new ones, though.
Twenty third century
The Outrageous Okona - Stano Riga, who "specialised in jokes about quantum mathematics."
Violations - Iresine Syndrome, first diagnosed that century
If Wishes Were Horses - subspace rupture in the Hanoli System in the mid twenty third century.
Trials and Tribble-ations - Dax likes the 23rd century designs of tricorders, etc; by the end of the 23rd century, tribbles had become extinct from their homeworld
Flashback - Hikaru Sulu doesn't resemble his Starfleet HQ portrait because "holographic imaging resolution was less accurate."
Cause and Effect - Bateson thinks it's still 2278.
"Hundred years ago" from the 24th century (so, the 23rd)
Pen Pals - Selcundi Drema's fifth planet shattered within the last 150 years (2365-150=2215)
The Vengeance Factor - Gatherers hadn't yet split off from Marouk's culture - violent clan warfare - only the Gatherers eventually remained that way - others overcame (2366-100=2266)
A Man Alone - Dax has been trying to master the Altonian brain teaser for 140 years or so. (2369-140=2238)
Equilibrium - Jadzia has a vision of members of the Trill Symbiosis commission, wearing uniforms from over a hundred years ago (2371-100+=2271, at least)
Melora- 150 years ago, the last time Dax made a relationship work.
Broken Link - Klingons relinquished control of the Archanis IV a hundred years ago. (2372-100=2272)
The Omega Directive - Omega particle first synthesized over a hundred years ago by Ketteract (portrayed in the TOS novel Cloak) (2374-100+=2274, at least)
Think Tank - Bevvox founds the think tank over a hundred years ago (in the Delta Quadrant, though, although Bevvox did so after"wandering the galaxy on his own for a few millennia.") (2375-100+=2275+, at least)
Life Line - This exchange between The Doctor and Troi -
Muse - a theater on Kelis' planet used to be a temple for sacrificing persons on (2376-100=2276) (Delta Quadrant)
Prophecy - Kohlar's grandfather was part of a Klingon sect looking for the Kuvagh'magh (2377-100=2277)
I've added a few new ones, though.
Twenty third century
The Outrageous Okona - Stano Riga, who "specialised in jokes about quantum mathematics."
Violations - Iresine Syndrome, first diagnosed that century
If Wishes Were Horses - subspace rupture in the Hanoli System in the mid twenty third century.
Trials and Tribble-ations - Dax likes the 23rd century designs of tricorders, etc; by the end of the 23rd century, tribbles had become extinct from their homeworld
Flashback - Hikaru Sulu doesn't resemble his Starfleet HQ portrait because "holographic imaging resolution was less accurate."
Cause and Effect - Bateson thinks it's still 2278.
"Hundred years ago" from the 24th century (so, the 23rd)
Pen Pals - Selcundi Drema's fifth planet shattered within the last 150 years (2365-150=2215)
The Vengeance Factor - Gatherers hadn't yet split off from Marouk's culture - violent clan warfare - only the Gatherers eventually remained that way - others overcame (2366-100=2266)
A Man Alone - Dax has been trying to master the Altonian brain teaser for 140 years or so. (2369-140=2238)
Equilibrium - Jadzia has a vision of members of the Trill Symbiosis commission, wearing uniforms from over a hundred years ago (2371-100+=2271, at least)
Melora- 150 years ago, the last time Dax made a relationship work.
Broken Link - Klingons relinquished control of the Archanis IV a hundred years ago. (2372-100=2272)
The Omega Directive - Omega particle first synthesized over a hundred years ago by Ketteract (portrayed in the TOS novel Cloak) (2374-100+=2274, at least)
Think Tank - Bevvox founds the think tank over a hundred years ago (in the Delta Quadrant, though, although Bevvox did so after"wandering the galaxy on his own for a few millennia.") (2375-100+=2275+, at least)
Life Line - This exchange between The Doctor and Troi -
Though that says more about tech advancement than personal opinions.DOCTOR: You won't even look at my research. From the moment I arrived, you've berated me, treated me like an antique. Well, let me tell you something. Antique or not, I took a huge risk coming here. I had to plead with my Captain, leave my ship without a surgeon.
TROI: Doctor. Imagine that your programme was seriously damaged, and the only person who could repair you was an engineer from, say, a hundred years ago. Would you feel comfortable with that?
DOCTOR: If he were skilled, intelligent, creative.
TROI: Honestly, Doctor? A hundred years ago?
DOCTOR: Well, I suppose it would give me pause.
Muse - a theater on Kelis' planet used to be a temple for sacrificing persons on (2376-100=2276) (Delta Quadrant)
Prophecy - Kohlar's grandfather was part of a Klingon sect looking for the Kuvagh'magh (2377-100=2277)
Friendship One - contact lost 130 years ago (2378-130=2248)KOHLAR: More than a hundred years ago, my great-grandfather was part of a sect which believed the Empire had lost its way. They discovered a sacred text. It told them to embark on a journey to a distant region of the galaxy.