Retroactive continuity, known as a retcon for short, is the alteration of previously established facts in a fictional work, either through the addition of new, conflicting information – be it in dialogue or on screen – or by visually altering the original work. The Star Trekfranchise has had numerous examples of such material.
Notable examples[]
The first such example was the differences in the Galaxy class studio models after the addition of Ten Forward in TNG Season 2.
The Trill also saw a noticeable re-envisioning between TNG and Star Trek: Deep Space Nine, when the character of Jadzia Dax was created to look less like the first on-screen Trill, Odan, and more like the Kriosian, Kamala.
Retconning became especially prominent when episodes of Star Trek: The Original Series and Star Trek: The Next Generation were remastered. Examples primarily included changing the information on display screen graphics when an episode was remastered. The information they originally contained may have been comprised largely of in-jokes that were never intended to be read; remastered footage would have made these nonsense graphics legible.
Retcons were very predominant with the premiere of Star Trek: Discovery had premiered, which introduced a radically new appearance for the Klingons. Whereas a conscious attempt was made to "justify" the difference between TOS and TNG Klingons in as far as noticing the difference in DS9: "Trials and Tribble-ations" and explaining the difference in ENT: "Divergence", the same cannot be said for their appearance on DIS. The Klingons that appeared subsequent to DIS's first season were in a style much closer to the TNG era (such as in "The Broken Circle").
The end of the first season introduced a redesign of the Constitution-class from the "classic" 1960s look. This had also previously occurred with the reboot of the franchise with the J.J. Abrams' series of films, beginning with Star Trek.
The premiere of Star Trek: Strange New Worlds, which revised the ethnicity of key characters, such as those of Robert April and Mr. Kyle. According to Trevor Roth, they sometimes "bend the canon" to fit a story need, and with regards to the changes in ethnicity, he said they did so in an attempt to bring more diversity to the casts of the various series, i.e., less white males, as was often depicted in TOS. (Personal conversation with Roth per User:Renegade54)
