Since Ace Attorney cases take place in various points in its timeline, this was bound to happen.
- In Trials and Tribulations, the first case is a prequel, and it features normally-bald prosecutor Winston Payne with hair and a tougher attitude: he loses both when you win and becomes more like himself from the previous games.
- There's an interesting example of this in the third case of Investigations: Examining the stage area after it's been reconstructed by Little Thief will show a Gavinner's symbol (the stylized "G"), and examining the sign next to the stage advertises not only the concert, but also a "battle of magic" between Max Galactica and Troupe Gramarye. The first is especially interesting, because in the flashback case in Apollo Justice, Klavier mentions that his band recently got popular.
- The fourth case of Investigations is practically made of this, due to being a flashback to four years before the beginning of the series. References range from Miles commenting on the fire extinguisher used to clonk Phoenix over the head in 2-1 to more serious matters such as the crimes and execution of Manfred von Karma. It turns to Tearjerker when Franziska mentions that she can't imagine what she'd do if her father died.
- The DS remake of the first game added a fifth case, which included references to the Phoenix Wright games that had been released by then. For example, if you checked around the evidence storage room, you'd find the bug sweeper that Phoenix would eventually use in Justice for All, complete with Gumshoe noting that it might become useful in the future.