On occasion, the writers of Battlestar Galactica will forget or ignore a critical statistic, plot point, or character development in the development of episodes.
Two situations can occur in this instance. The writers may acknowledge or ignore the error. Battlestar Wiki keeps track of such mistakes, acknowledged or not, in the article, "Continuity errors (RDM)." Rarely, the writers may adjust the issue in a later episode. As a result, the established facts of the show to-date are changed. This is known as a retcon, a portmanteau for retroactive continuity.
Retcons are different from separate continuities, a designation used on Battlestar Wiki to allow officially-licensed Battlestar Galactica stories (Original or Re-imagined universes) from novels, comics and the like to be listed in the wiki without wrecking the canonical aired content of either series.
Additions[edit]
The Re-imagined Series often creates retcons through the use of additions to the series by way of flashbacks and deleted scenes. Generally these additions don't contradict aired content but add interesting or insightful background to a character or event that was specially created for the episode or outtakes initially removed during editing for various reasons. The flashback scenes of the post-war lives of William Adama and Saul Tigh in the episode "Scattered" is a good example of this. The same is true for a scene, added to the episode, "Scar," where Kara Thrace pleads unsuccessfully for a rescue mission to Caprica to the president and Commander Adama.
Alterations[edit]
Alterations to the series content are rare, if nonexistant in the Re-imagined Series. An alteration is a scene that basically tells the viewer, "What you saw before didn't really happen." The most famous alteration retcon ever made on TV was the death of the character Bobby Ewing in season 8 of the TV show, Dallas. An entire season went on without the character until another character awakens in season 9 to find the before-deceased character in the shower, which dismissed the entire previous season as a dream.
Reboots[edit]
Reboots, also known as a "subtraction," is a drastic elimination of past storylines through a substantially new storyline. Reboots frequently cause great controversy with the fans of the original work. Comic book publisher DC Comics has done this many times with its superhero comics, eliminating complicated and confusing storylines and characters to reset the canon of the characters.
The Re-imagined Series itself is a "reboot" of the Original Series, discarding practically everything from the Original Series and recreating new versions and variations of characters, histories, ships and more. One key change in the Re-imagined Series that caused much controversy initially was the change of the male Original Series character known as Starbuck into a female named Kara Thrace, with her pilot callsign as "Starbuck."