Warning: light spoilers for Deadpool 2 below.
Suffice it to say, Deadpool 2 has a lot going for it. With a bangin' soundtrack (that features none other than legendary icon Celine Dion), a pretty wild postcredits scene, and the very lucky Domino, round two of the growing franchise is delightfully action-packed and entertaining. Then, of course, there are the tons of cameos. Sure, Brad Pitt's small role was easily the most epic, but there's one other surprise appearance that's a direct callback to the first film: all the X-Men!
The moment in question comes while Deadpool is recovering at the mutant academy after attempting to blow himself up. He makes an off-the-cuff remark about how empty the mansion is, and then we pan over to a room with an open door; inside, we see Quicksilver (Evan Peters), Professor Xavier (James McAvoy), Beast (Nicholas Hoult), and even Cyclops (Tye Sheridan). One of them quickly closes the door before Deadpool spots them. The joke is a callback to the first movie, where Deadpool points out that Colossus and Negasonic Teenage Warhead were the only X-Men the studio was able to "get" for his low-budget superhero film.
If you're curious about the real reason behind the massive omission, screenwriter Paul Wernick explained his reasoning for shrinking the cast of characters back in 2016. "We didn't want to populate his world with X-Men. They're two separate franchises, and I think had we done that, we would have been making a mistake. Even if we did have the budget." If you read between the lines, it sounds like a mix of circumstances. Perhaps the first movie really didn't have enough funds to pay for all those high-profile X-Men appearances, so the creative powers that be decided to lean into it. So, we have some "D-list" X-Men in Deadpool, and the antihero himself gets to joke about it.
When it comes to the sequel, there probably was a bigger budget. Even in 2016, though, Wernick wanted to follow the same path. "Going into the sequel, we are embracing this idea that it's a small budget movie," he said. "And we're not gonna populate it with the entire X-Men cast." Since Deadpool is intent on running with jokes as far as they'll go, it all makes perfect sense. And frankly, that funny cameo moment has a way better payoff than a crowded movie with the biggest names of the franchise. We'll take it.