Star Trek Discovery's big mystery of season 2, the Red Angel, may hold the key to an even bigger mystery - the discrepancies in the timeline between the CBS All Access show and prior Star Trek series. After gaining a new captain in the guise of the Enterprise's Christopher Pike - played with charm by the departing Anson Mount - Michael Burnham and the crew of the Discovery have been on the trail of the Red Angel, a mysterious entity that left strange signals across the galaxy, and is somehow connected to Burnham's adoptive brother, Spock.
The Red Angel was eventually revealed to be Dr. Gabrielle Burnham, Michael's mother who was believed killed in a Klingon attack two decades earlier. Dr. Burnham has been using escaped her demise by using the Red Angel suit, which turned out to be time travel technology she was developing for Section 31, the morally ambiguous black ops arm of Starfleet. Dr. Burnham jumped 950 years into the future, where she found that all life in the galaxy had been wiped out by Control, the malevolent artificial intelligence that Section 31 utilized extensively during the Klingon war.
Dr. Burnham spent the next 20 years of her life jumping back into the timeline, attempting to thwart Control, but after hundreds of attempts, she's yet to find a way to prevent its universal destruction. What's notable about her failure, however, is that her logs indicate she jumped back in time over 800 times, and while she may have never achieved her ultimate goal, she may have inadvertently caused subtler changes in the timeline.
As many a Star Trek fan will explain - often at considerable volume - there's really no way for Discovery to link up to Star Trek: The Original Series in terms of visual aesthetics and technological abilities in the ten year gap between them; there's simply no rational way the sleek, CGI-enhanced Starfleet ships of Discovery could morph into the simplistic, 60s retro sets of TOS in the span of a decade. Some of this is just the reality of making television shows 50 years apart, but Star Trek has often strived to fill in such seeming inconsistencies, like the Klingons' changing appearances or, perhaps the most germane example, the consequences of time travel and alternate realities set up in the J.J. Abrams reboot films.
It's possible Dr. Burnham could have nudged the timeline in one direction or another through all of her time travel missions, accidentally creating changes in the pace at which Starfleet developed their technology, which would explain why there are holograms and touch panels instead of plywood and knobs on the Discovery bridge. This actually wouldn't even be that big of a leap for the show at this point; it's already been made explicit that Dr. Burnham's time travel missions altered Spock's life in ways that make it possible to reconcile this decidedly different version of the character with the iteration played by Leonard Nimoy over five decades.
Star Trek has rarely gotten into the granular repercussions of time travel - with the notable exception of the classic TOS episode "The City On The Edge Of Forever." Star Trek's time travel stories tend to feature more plainly lighthearted scenarios - Kirk and Spock stealing a pair of extinct whales from the 1980s, Picard and crew meeting Mark Twain - than Doctor Who scaled temporal crises. But if nothing else, Star Trek: Discovery has proved it's willing to go places no other Star Trek show has gone before, and it may finally be treating time travel like the invaluable science fiction tool it is.