Backported Development

Sometimes, characters develop over the course of a show. And sometimes, shows will present new scenes from earlier time periods. And sometimes, characters in a flashback will exhibit character unlike the way they acted before the time the flashback is occuring.

For example, when Bob started on the show in 1991 he was characterized as a Jerkass, but became a Jerk with a Heart of Gold in 1993, and then just became a nice guy by 1995, but is shown in a recent flashback to 1990 to have been a nice guy in 1990, with no explanation/extenuating circumstances.

Usually, this happens unintentionally due to Flanderization and Characterization Marches On, often due to the too many flashbacks to track characterization in an Expansion Pack Past. This might be used to Retcon an existing flashback, maybe because it also had to be reshot since it was a Flashback with the Other Darrin. If you not only pick up your old characterization but also your old visual style, it's a Retraux Flashback.

Trope name comes from "backporting", a concept in software development where features from a new codebase are imported to an older branch of development.

Comics

 * Judge Anderson, a psychic Judge in the Dreddverse, was a very flippant and easy-going character when she first appeared in Judge Dredd, though would get serious when the situation mandated it. As time went on, she became a rather serious character most of the time, and her dominant mood was vague despair at the shape of the world. In late 2010, possibly as part of the buildup to the new Dredd movie, Alan Grant started writing a Prequel series, Cadet Anderson, set during Anderson's days as a cadet. In the prequel series, she is a very serious character who wishes the world could be better, in seeming contrast to the fun and light-hearted lady who first fought Judge Death.

Film

 * In Star Trek Nemesis, they show a picture of Jean-Luc Picard when he was young, and for some reason, he was bald, despite the fact that his balding had everything to do with his age, as previously shown in the show. This also makes the villain quite baffling. However, Patrick Stewart himself really had lost his hair by this age, really muddling things.
 * Patrick Stewart apparently used his premature baldness to get his first theatre big break; he successfully convinced his bosses that he could play both old and young roles (wearing a toupee), so it was like getting two actors for free.

Live Action TV

 * In the first episode of Monk, they establish that he's so messed up because of the death of his wife. By the final season, he's suddenly been weird/crazy since he was a little kid (to the point where they're making Webisodes all about it called "Little Monk"), in a way completely destroying the emotional impact of his wife's death, as well as making his suspension from the force, and his inability to be officially brought back on, simply odd.
 * Fridge Brilliance dictates that he was always messed up except for the brief moment in his life when he was with Trudy.
 * It was a part of his character from the pilot on that his quirky way of looking at things was what made him a great detective, but Trudy's death destroyed his ability to keep it under control. He is said to have recovered a great deal by the time the show begins.
 * Averted in Lost, which cuts around with its flashbacks, but keeps characterization as established when the scene takes place (noticeably when Shannon and Boone are shown shortly around the time of the crash, Shannon is still doing nothing but complaining.)
 * Series VII of Red Dwarf contains flashbacks to shortly after the revival of Rimmer (Series I). The style of the 'H' on his head and his uniform were the ones from Series VII.
 * Kryten's changed appearance is handwaved by the explanation that Lister rebuilt him after a spacebike crash, yet a few episodes later we see a moving photograph of Kryten pre-crash and he looks (and speaks) the same as post-crash. Additionally, the other Series 4000 mechanoid we meet, Able, looks like the "rebuilt" Kryten as do his spare heads in "DNA" and "Beyond a Joke".
 * The flashback in series 2's "Stasis Leak" to before the accident maintains the set design and props that were added to the bunk room in series 2.
 * From Series 7 onwards, Kochanski became a main character, but was played by a new actress. This was introduced by having her be from a parallel dimension, so the difference in appearance would not be too jarring. However, flashbacks in Series 7 and 8 to before the time of Red Dwarf's accident have this newer actress rather than the original actress who played her, thus spoiling the continuity.
 * My Name Is Earl had this twice, both with heavy lampshades. Two flashbacks saw Earl being the good guy despite the show's entire premise being he was an awful person until he "discovered" Karma. One featured Earl saving Joy from a killer bee while his cousin cowered in a tent, and the other was his reasoning for raising two kids who were not his own. Both were described, if memory serves, as the only good thing he did before he made the list.
 * Star Trek the Next Generation had this in the series finale. The captain's chair shown in the past is the same one as the then-current chair, with little lights under the arm-rests instead of the folding panels the first season chair had.

Video Games

 * In Sonic Adventure 2, there are numerous cutscenes which show one of the characters fifty years ago. Throughout the game, he acquires numerous bits of equipment, and the items you've got are visible on his character model even in the flashback cutscenes.
 * The first Sonic Adventure game has a flashback to Sonic CD, where Amy lacks her signature uniform. They apparently didn't feel like making another model for a few seconds worth of footage.
 * A very minor instance occurs with Classic Tails and Dr. Robotnik in Sonic Generations, in which they are voiced by their current incarnations' actors. This isn't too much of a Backported Development considering they never spoke in the old games at all, but it does mean that throughout his life, Eggman went from sounding like Mike Pollock to sounding like Deem Bristow... and then back to sounding like Mike Pollock again.
 * Soul Calibur: Broken Destiny's version of Yoshimitsu strongly resembles his Tekken 6 appearance, where he looks like an alien rather than a samurai which is what he's supposed to be in the Soul Series (it takes place centuries earlier). In the first Tekken, Yoshimitsu looks more like a knight, which is more consistent with how he would have looked when the Soul Series is set.
 * Averted in Final Fantasy VII: Crisis Core, where despite having undergone Flanderization in sequels and spinoffs, Cloud acts really close to his original characterisation (or at least as close as you'd reasonably expect considering how much younger he is). Aeris also returns to being bossy and intelligent rather than being Incorruptable Pure Pureness and Yuffie goes back to being sneaky, sarcastic and manipulative rather than a goofy Genki Girl.
 * Portal 2 changes the design on many items such as the elevators and the Material Emancipation Grills, yet when you return to destroyed areas from the first game they are fitted with the new design. Visiting "Old Aperture" later on reveals that these new designs were apparently in use in test chambers from decades before the first game took place.

Web Comics

 * This happens in MS Paint Masterpieces, where Ferretvision and current strips contradict eachother. In this case, though, it's a conscious retcon.