Early Installment Weirdness/Film

Examples of in  include:

Other Examples

 * The original The Pink Panther from 1963 was written to be about the thieves rather than Inspector Clouseau. It was in the sequel, A Shot in the Dark, where the series shifted to focus on Clouseau, and the recurring characters Cato and Dreyfuss were introduced.
 * Star Wars Episode IV - A New Hope has a number of elements that can seem strange in comparison to the series as a whole.
 * The film has a number of plot elements that were changed or outright retconned in the later canon, with Anakin and Vader as different people, Obi-Wan adopting his alias before Luke was born, Anakin being still alive when Luke was at least a child, the Jedi and the Force being widely considered a myth, "Darth" being a first name rather than a title, etc. A video showcasing all this exists here.
 * The lightsaber battle in 'Star Wars Episode IV - A New Hope is quite stiff and awkward compared to the more dramatic and gymnastic swordfights in later installments. According to Mark Hamill, the original lightsaber props had motors to rotate the "blades," making them too heavy and dangerous for any impressive Flynning. Also of note, Obi-Wan's lightsaber "flickers" in mid-battle, while most subsequent lightsabers do not.
 * Although Obi-Wan's been using this lightsaber for decades, and it's probably in disrepair- the crystal could be fizzling out after all this time.
 * Darth Vader's Leitmotif, "The Imperial March," does not appear until The Empire Strikes Back. The first film has more generic fanfare.
 * Carrie Fisher's infamous British accent ("slip through your fingers") as Princess Leia, which she seems to drop halfway through the first film.
 * There is also a Leitmotif for the Death Star, which is not used in "Return Of The Jedi".
 * In the original Friday the 13 th, Jason not only isn't the killer, he doesn't even appear save for a dream sequence. He becomes the killer in the second film but doesn't get his trademark hockey mask until the third. Also, in Part II, he's considerably less physically imposing than subsequent movies.
 * Throughout the Harry Potter films, more and more areas are added to Hogwarts, making the Hogwarts of the first film almost a kind of bare-bones version with, for example, nothing between the back of the castle and Hagrid's hut but a field of grass.
 * In the first two films, Professor Flitwick is an elderly-looking midget. From the third onward, he became a small man with brown hair and moustache. It was so unexpected that quite a few people joked that he now looked like Hitler. (the story is complicated: as Flitwick wouldn't appear in Prisoner of Azkaban, actor Warwick Davis was instead offered a cameo as the chorus conductor - credited only as "Wizard"; through Retcon, that guy became Flitwick in the fourth movie)
 * It's also worth noting that many of the films ongoing additions to the castle were invented for the screen - most notably the clocktower and pendulum, the covered wooden bridge and the small island in the lake - so it's likely a matter of the films wanting to establish themselves as being as faithful as possible to the books (which the first two films are, more so than each of the rest) and then getting more creative once they'd secured their audience. Other later-film additions like the Owlery and the Astronomy Tower were added when it turned out important scenes took place there in books that hadn't been published when the movies started filming. The Astronomy Tower in particular was a bit jarring to suddenly spring up after five films' absence, given that it's faithfully portrayed as being the tallest tower of Hogwarts Castle.
 * There's also a drift away from on-location shooting and towards soundstages. At the start of the series, they couldn't afford to build every room in Hogwarts, so there were only a few purpose-built sets and most of the Hogwarts interiors were filmed at various castles, cathedrals, and universities. As the series went along, they built up more and more sets, which was coupled with improvements in CGI technology. Harry Potter and the Philosopher's Stone was filmed at locations all across Britain, while Harry Potter and the Deathly Hallows - Part 2 was filmed almost completely at Leavesden Studios. Some places that were originally filmed on location were reproduced as sets later in the series, often accompanied by changes in design -- compare the hospital wing in the first movie to the hospital wing in the second movie onwards.
 * In the first movie, the students wore pointed hats with their uniforms during formal scenes in the Great Hall (you'll recall these hats being tossed in the air when Gryffindor won the House Cup). The hats disappeared in the second film and were never seen again. Probably because they looked rather silly.
 * How many people remember that First Blood was a depressing film about a Shell-Shocked Veteran fleeing the law?
 * If you watch Dr. No after other James Bond films, it'll be a shock: it's basically a hard-boiled detective story instead of a spy action thriller - mostly because the budget was low. The fight scenes and car chases are rare and short; the only gadget per se is a mook's Cyanide Pill (Q - here, Major Boothroyd, and not played by Desmond Llewellyn - only appears to change Bond's gun).
 * Even the opening sequence is all wrong. It starts with a series of weird electronic beeps, and the familiar theme doesn't play until Bond shoots the gun barrel, and even then it starts on the wrong cue (the big dramatic part of the song, instead of the actual intro). Then the barrel wiggles down to the bottom of the screen and the opening scene wipes in from-- oh? No, it moves on directly to the opening credits while still playing the Bond tune, over some colorful dots appearing all over the screen. Then it jarringly switches to some upbeat salsa music (note - not a theme song including the movie's title) over some colorful silhouettes of people dancing for a minute or two, when it again suddenly switches to a salsa rendition of "Three Blind Mice" over the silhouettes of the title mice, which then fade into the actual opening of the movie. To call that opening schizophrenic is being a little too kind to it.
 * In fact, the music-video Bond titles didn't appear in their best-known form until Goldfinger.
 * Toy Story. Watching the film 15 years after it was originally made, while the composition of the elements is still impressive, it is noticeable how certain textures (hair and fabric) are left rather ambiguous and that the faces of human characters other than Sid are often out of frame. This was due to the technology not yet being at point where it could render organic things realistically: it wasn't until The Incredibles that they took the plunge and made an entire film about people.
 * It's also strange because when stacked up against later CG toons, the film is remarkably low-key, lacking the bombastic flourishes that people grew to expect of the medium. The opening scene of the film is a child playing with his favourite toys, nothing more.
 * Evil Dead is more a Gorn horror film, rather than the horror comedy of the second. Also none of the other cabin members besides Linda is mentioned in the other films. Ash is far from the Catch Phrase spouting, Badass and Jerkass we see in the sequels, instead being a rather bland Final Girl played by a guy. The Necronomicon doesn't have that name and the look of it is completely different from the other films. And lastly, in a subtler example, the Deadites (which aren't named as such until the second movie) are originally just pissed off that the teenagers awoke them from their eons-long sleep, whereas in the sequels they implicitly want to Take Over the World.
 * Saw. In the first two films, Jigsaw is a brutal Serial Killer Complete Monster with an interesting MO. Also, the first film contains very little gore, and the second only contains a lot of blood, but nothing too explicit beyond that. The Torture Porn that the films became known for didn't really start until the 3rd film, at which point Jigsaw was toned down considerably into a very deranged man with a tragic past, but with his heart in the right place. While still a psychotic villain, he is no longer the Complete Monster of the first two films.
 * Road To Singapore is a fairly typical adventure-comedy movie, and doesn't do much in the way of Breaking the Fourth Wall.
 * The first Transformers movie is a more straight-forward story with a relatively short number of robot characters (Sequel Escalation and Serial Escalation were heavy in the two movies that followed). Also, while Bumblebee drops Sam and Mikaela out of his vehicle mode before transforming into his robot mode to fight Barricade, the sequels have the transformations fast enough to safely eject any passengers and quickly convert into robot mode in one quick go.
 * If your knowledge of Twilight comes from Popcultural Osmosis, you'll find the first movie awfully strange. It's essentially a low-budget indie (a very successful one, of course) and it feels like it. There are only the most basic special effects and it generally just feels "small". In contrast, the sequels had higher budgets, so they feel bigger and have a blockbuster "sheen" which the original lacked. Taylor Lautner does appear as Jacob in the first film, but he's just barely in it, never mentions being a werewolf, and (gasp!) keeps his shirt on the whole time.
 * To be fair, Taylor Lautner wasn't as impressive physically in the first movie. It's why they were going to recast his character, but he was dedicated to providing the fans continuity and bulked up considerably.
 * X-Men: First Class plays with this thematically, being set around the Cuban Missile Crisis. Professor Charles Xavier for instance is shown to be a rather cocky beatnik in his youth, while Erik (aka, Magneto) was a Nazi Hunter who had no qualms using guns alongside his powers.
 * The original X-Men film counts because it acts more like a character driven sci-fi drama than a superhero film.