Retroactive continuity
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 dialog or on screen – or by visually changing the original work directly.

Star Trek has had large amounts of such material, especially when episodes of  and  were remastered, and after  had premiered. Examples include: changing the information on display screen graphics when an episode is remastered; the Discovery redesign of the  from the "classic" 1960s look; and the differences in the Galaxy class studio models after the addition of Ten Forward in TNG Season 2.

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fr:Continuité rétroactive
Plot devices