History Recap / StarTrekDiscoveryS5E04FaceTheStrange

* CanonWelding: The Krenim from the ''Voyager'' two-parter "Year of Hell" are revealed to have been a faction in the Temporal Cold War, which makes sense given their more esoteric time travel-based technology.

* CanonWelding: The Krenim from Voyager are revealed to have been a faction in the Temporal Cold War, which makes sense given their more esoteric time travel-based technology.

* YouAreBetterThanYouThinkYouAre: The reason past Burnham attacks future Burnham is that she thinks there's no way she could possibly become a Starfleet Captain after disgracing herself through her mutiny at the beginning of the series, therefore the future version of her must be a shapeshifter trying to fool everyone. To get her cooperation, Rayner has to convince her of this trope.

* TimeTravelTenseTrouble: During the first time jump, Burnham and Rayner find themselves at the start of season 3 as Bur ham in the Red Angel suit is leading ''Discovery'' through the temporal wormhole.

* TimeTravelTenseTrouble: During the first time jump, when Burnham and Rayner find themselves at the start of season 3.

* YouAreBetterThanYouThinkYouAre: The reason past Burnham attacks future Burnham is that she thinks there's no way she could possibly become a Starfleet Captain after disgracing herself through her mutiny at the beginning of the series, therefore the future version of her must be a shapeshifter trying to fool everyone. To get her cooperation, Rayner has to convince her of this trope.

* SanDimasTime: The Time Bug [[YearOutsideHourInside shatters linear time for the crew]] but is still in progress from the time it was activated, so Burnham and Rayner have to manage things in small bites before resetting to their original positions in the ready room. Luckily, the length of time increases with each jump, allowing a little more to be done in each cycle. It's said to have been a weapon during the Temporal Cold War and could disable a ship for months until the device ran out of power. Adira comments at the end that six hours had past instantly for everyone else.
* SetRightWhatOnceWentWrong: One of the earlier time jumps was to their relative future about 30 years on, where Discovery was a barely functioning husk outside a destroyed Federation Headquarters. Zora said the ship was out of commission for too long, allowing Moll and L'ak to get ahead of them on the Progenitor mission and the technology was sold to the Breen who quickly wiped everyone else out. Burnham and Rayner then had motivation to fix their situation faster.

* UnusuallyUninterestingSight: Burnham and Rayner are wearing 32nd Century uniforms but frequently have brief interactions with characters from the 23rd Century who nonetheless don't question the foreign uniform. A random mechanic during dry dock construction accepts Raynor as a senior officer. In a time set during season 1 Linus interacts with present-day Burnham as the pariah she was at that time, but after an uncomfortable silence merely comments that red suits her.

* GroundhogsDayLoop: Played with, the time jumps are random according to the time period they arrive at but linear to Burnham and Rayner, who end each jump in the same location. So while they physically start from the same location each jump and carry knowledge they discover about the situation from prior jumps, they still have to quickly check records to see what is going on at that moment.

* SurprisinglyRealisticOutcome:
** Downplayed, but the timeline reset of "Year of Hell" did ''not'' remove temporal weaponry from the Krenim Imperium's arsenal. It was established they ''already'' had access to stuff like the Chroniton Torpedoes ''before'' Annorax embarked upon his mad quest. Destroying Annorax's Weapon Ship and resetting the timeline thus did ''not'' retroactively erase those earlier weapons since they predated the Weapon Ship's creation and very first temporal incursion. Whether or not the post-reset Annorax pursued his weapons research (as per the ambiguous ending of "Year of Hell") is irrelevant; the temporal genie was ''already'' out of the bottle. So, with that kind of technology and weaponry still at their post-reset disposal (and almost certainly further refined and developed over the subsequent centuries), it's completely unsurprising the Imperium ended up as players in the Temporal Wars.
** The new Temporal Accords may have outlawed all forms of time travel and mandated that such technology be destroyed, but that doesn't mean that all of it actually was. Some illicit devices are still available on the black market.

* UnusuallyUninterestingSight: Linus in the 23rd century sees present-day Burnham wearing a red uniform that is nothing like current Starfleet standard, and after an uncomfortable silence merely comments that red suits her.

** Downplayed, but the Krenim having participated in the Temporal Wars. Either the post-timeline reset Annorax continued his temporal weapons research (as the ending of VOY's "Year of Hell" left hanging), or someone else had the same idea (or alternately Annorax abandoned his research and someone else picked up where he left off down the road).

* SurprisinglyRealisticOutcome: Downplayed, but the Krenim having participated in the Temporal Wars. Either the post-timeline reset Annorax continued his temporal weapons research (as the ending of VOY's "Year of Hell" left hanging), or someone else had the same idea (or alternately Annorax abandoned his research and someone else picked up where he left off down the road).

* YouHaveGotToBeKiddingMe: Rayner's expression when told about how Stamets is immune to the time loops.

* BackForTheFinale: Well final season, but Airiam makes an appearance in the final jump.

* BavarianFireDrill: Burnham and Rayner are sent back to ''Discovery'' while it's still in dry dock, and quickly bluff an engineer into thinking they're there for an inspection.
* BottleEpisode: Save the opening scene with its exterior shot, the entire episode takes place aboard ''Discovery''. {{Zigzagged}} in this case as the sets have to be redressed for each time period, ''and'' the costuming is through the roof due to the show featuring the return of the blue-pajamas uniforms from the first three seasons, not to mention those seasons' hairstyle and makeup.

** Rayner previously warned about a resurgent Breen empire at his hearing. They end up being the ones Moll and L'ak sell the Progentior technology to in the BadFuture.

* ReducedToDust: The Krenim time bug is equipped with temporal shields that create a bubble of hyper-accelerated time, which means anyone or anything that attempts to touch it will age into dust within moments. The only way to counteract it is with {{Technobabble}} involving relativity and the warp bubble of ''Discovery''; it succeeds, but Rayner's hand doesn't come out unscathed. Fortunately, 32nd century medical technology fixes him right up.

** Stamets, meanwhile, retains his past immunity to temporal changes thanks to his tardigrade DNA. Unfortunately, he is instead subject to MentalTimeTravel, which isn't helpful because in several versions he is either injured, dead, or simply not present.

* XanatosGambit: Moll and L'ak's Krenim bug. Ideally, ''Discovery'' remains trapped jumping through its own timeline until the bug ran out of power, which means Moll and L'ak can pursue the next clue at their leisure. In the BadFuture, by the time Starfleet figured out what happened to ''Discovery'' and rescued them, Moll and L'ak had long enough to discover every clue and sell the technology once they acquired it. Even though ''Discovery'' averts this future, they are still waylaid long enough for Moll and L'ak to have taken the lead in the race to the next clue.

* CompleteTheQuoteTitle: The title is a line from the Music/DavidBowie song "Changes", which also features the line "Time may change me, but I can't change time".

* AllForNothing: Downplayed, but the events of VOY's [[Recap/StarTrekVoyagerS4E8YearOfHell "Year of Hell"]]. Despite the efforts of Janeway and the destruction of Annorax's weapon ship, the Krenim still clearly and ultimately pursued temporal weapons research in the reset timeline.