Development Hell: Gyakuten Saiban 5 was first hinted at in 2007 then lay dormant for nearly five years before we even got a logo in early 2012. A demo was playable at TGS 2012, and it'll finally be released in 2013.
Executive Meddling: Shu Takumi wanted to make an entirely new cast in Apollo Justice, but Capcom's higher-ups told him he had to put Phoenix in it. Additionally, the jurist system being introduced was also a requirement due to changes in the Japanese legal system, which caused the hotly debated storyline involving Phoenix to be developed.
Fan Nickname: Phoenix in Apollo Justice is HoboPhoenix, Naruhobo, or Hobonix, and Daryan Crescend is "Dickhead" for, well, obvious reasons.
I Knew It: The fandom were correct in assuming that Ema's button was a spycamera and that Edgeworth is secretly a big fan of the Steel Samurai.
Jossed: However, the fandom was NOT correct to assume that Trucy was Phoenix Wright's biological daughter or that she's actually an older Pearl.
When the flashback case featuring Gregory Edgeworth was announced to involve Manfred von Karma, people began suspecting that this was the case that led to von Karma's penalty, and by extension the DL-6 incident that basically sparked all the events of the series.
When the first details of Dual Destinies at TGS, some people guessed that Apollo was related somehow to the courtroom bombing that was the focus of the game's first case. Fast forward to March 2013, when the first images of injured Apollo showed up. Fully confirmed a month later, when a playthrough of the updated demo outright stated that Apollo was protecting someone from the debris produced by the explosion.
Someone on this very site's WMG page managed to correctly guess Fulbright as Dual Destinies' Big Bad. It's a little more complicated than that, though.
No Export for You: The series is infamous for it, sometimes taking years to make international ports (if at all):
Phoenix Wright: Ace Attorney for DS — Japan and US got it in 2005, Europe in 2006, but Australasia didn't get it until March 8, 2009.
Trials and Tribulations for DS — Europe got it a year after the US, still no official Australasia release.
Original trilogy 3DS rerelease — due 2014 for Japan, no mention of US release until E3 2014, but no confirmed release date.
Dual Destinies — again, not even a mention of an official Australasian release.
Ace Attorney Investigations — western release was almost a year behind Asia releases.
Gyakuten Kenji 2 — released 2011, still zero plans to export anywhere despite the major demand for it; only fan-dubbed versions are available in English.
Phoenix Wright Vs Professor Layton — 2012 release, took until 2014 for worldwide releases.
Even the movie isn't excempt — the DVD and Blu-ray was released Q3-2012 for Japan, and Q2-2013 saw subbed releases for only Germany and Australia. To clarify: they made one foreign sub for all of Europe, and still haven't allowed a USA/EU release despite already making and releasing a version with English subs.
Sequel First: Apollo Justice was released before Trials and Tribulations in Europe, due to complications on the latter's rating.
As noted in No Export for You, several audiences have suffered through this; assuming you're even getting a release, don't expect it any time soon or in the correct order.
Kristoph's early designs included a kimono getup that made him look he'd fit right in with the Gotei 13. Franziska was a much colder-(but sexier-)looking woman note One design looked like Mia Fey. who licked her whip, Young Mia a motorcyclist, Phoenix's hair-spikes hung downward (and were more natural), Pearl had plain, short black hair (and later Odango Hair), and Dahlia had a hell of a lot of different appearances, all equally deceptively sympathetic.
Colias has an unused sprite, which frankly enough looks quite silly and could be considered his "damage" sprite.
There's a whole lot of unused dialogue in Investigations 2 's first case. The first Logic deduction was going to be entirely different (and implied the weather would play a significant role in the mystery), and there's a whole lot of cut dialogue with Winston Payne, though he still doesn't get a proper sprite.
Non-Specific Franchise Trivia
After the original trilogy ended, there have been many instances where important characters were referenced at one point but their names were never given and otherwise never appeared.
Although a few references by Edgeworth, Franziska, and Larry are made, Phoenix's name is never mentioned in Ace Attorney Investigations.
Phoenix, Maya, and Pearl actually DO make an onscreen appearance if you look out onto the lake during a certain chapter in case 3. However, no one seems to notice them nor can the player see their faces.
In Ace Attorney Investigations 2, Phoenix and Maya can be briefly seen in case 5, and during the ending Edgeworth flashes back to his first court encounter with Phoenix. He still isn't named, however, his "Objection!" is silent, and the camera cuts away just before we see him in court.
Though Phoenix and Ema drop hints, we never hear of Maya or Edgeworth in Apollo Justice.
Every playable lawyer bar two has defended Phoenix Wright at some point. Phoenix himself in the second half of Turnabout Sisters, Edgeworth in the "trial" of Edgeworth's stolen lunch money, Mia Fey in Turnabout Memories, and Apollo Justice in Turnabout Trump. The exceptions are Gregory, who is related to one of the lawyers who did defend Phoenix, and Athena, who works with two of the lawyers named above.
As of Dual Destinies, Phoenix Wright is the only character who has appeared in all seven games of the franchise, cementing his position as the most important character in the series (note that Phoenix only had cameos in the Investigations games). However, before DD there was some other characters who shared that position with him
Gumshoe, Payne, and the Judge were the other characters who shared the privilege with Phoenix of appearing in every game until Investigations 2 came out; Gumshoe is the only one to have testified in every game up to that point, while Payne is the only one who had never testified.
In Investigations 2, the judge doesn't appear so it left Payne, Gumshoe and Phoenix as the only ones to appear in every game at the time. Also, Payne had appeared in every single first case of every game up to this point.
Judging by one of the Japanese trailers, Simon Blackquill is the only antagonistic Lawyer to have a voiced Catch Phrase that isn't Objection. The only previous antagonists to have voiced catchphrases that weren't Objection were Lang (Not so fast!) and Mikagami (Overruled!), an investigator and a judge, respectively.
The Ace Attorney series is amongst the top 30 selling series in Capcom history.
Ace Attorney Investigations was originally going to star Ema Skye.
In the course of seven games, you get to play as many characters and while Phoenix, Mia, Edgeworth, Apollo, Athena and Gregory are the main characters who the player is supposed to use, there have been instances where other characters were playable in brief portions of the games.
Maya was briefly playable in the last case of Justice For All.
You very briefly play as Lamiroir near the end of Turnabout Succession.
You briefly control Gumshoe in AAI2.
As of Ace Attorney Investigations, Gumshoe has appeared in the most cases throughout the series so far (if one doesn't count cameos by Phoenix in cases he does not play a role in).
If deKiller is indeed the killer of AAI2 case one, he will have the dubious honor of being the only character to be the killer in more than one game. Unless Von Karma is counted for the DL-6 case appearing live in the same game, or Morgan Fey orchestrating 3-5 and the death it results in counts as a murder.
Similarly, Manousuke Naito has the dubious honour of being the only character who's both a killer and a victim in the same game.
Unless of course, you include Manny Coachen from the first Investigations game.
The earliest chronological case has changed three times: first to Turnabout Beginnings in Trials and Tribulations, then Turnabout Reminiscence in Ace Attorney Investigations, and finally the IS-7 Incident in Ace Attorney Investigations 2.
Also the IS-7 Incident is the only case which is set in the past to when the game came out. The case is set in 2001, whereas the game came out in 2011. The closest is Turnabout Reminiscence, which is set in 2011 and the game came out in 2010.