The following post contains SPOILERS for Captain America: Civil War.

Marvel prides itself on the deep interconnectedness of its cinematic universe. Events in one movie continue to the next, and plot threads from years earlier continue to resonate in the lives of the company’s characters. Captain America: Civil War incorporated elements of almost every single Marvel movie that preceded it. Even relatively forgotten MCU entries, like The Incredible Hulk, were rendered important in its massive comic-book tapestry. (Hulk nemesis General Ross, played by William Hurt, made his first Marvel appearance since Incredible Hulk in Civil War.) In Marvel, everything counts and everything connects.

At least it all connects as far as the movies go. Although they’re theoretically set in the same cinematic (or televisual) universe, Marvel’s TV series have typically stayed far afield of their big-screen brethren. Characters move from movies to television, like Agent Coulson of The Avengers and Agents of S.H.I.E.L.D., but they rarely go the other direction. (Coulson hasn’t been back on an MCU movie since the premiere of Agents of S.H.I.E.L.D. in 2013.) Even with both sides of the conflict in Captain America: Civil War, and both sides desperately recruiting superheroes to help their cause, none of the characters from Marvel’s Netflix series like DaredevilJessica Jones, and Luke Cage appeared (or were even alluded to) in the movie.

For hardcore Marvel fans, the separation between the two supposedly connected worlds can get very frustrating. That situation gets directly addressed in the directors and screenwriters’ commentary for Civil War on the film’s new Blu-ray. During one section of the (really thorough and very interesting) chat, directors Anthony and Joe Russo and writers Christopher Markus and Stephen McFeely discuss whether Marvel movies are essentially television, as some critics have argued, and they also point out one small but crucial moment where Marvel TV directly seeded something that paid off in this Marvel movie.

That crossover comes up in the scene just over an hour into the film where Tony Stark (Robert Downey Jr.) tries to convince Steve Rogers (Chris Evans) to sign the Sokovia Accords just before Bucky Barnes (Sebastian Stan) is brainwashed by Helmut Zero (Daniel Bruhl). After Tony tells Steve that he broke up with Pepper Potts, the conversation turns to Tony’s parents. His dad, Howard, helped create the formula that turned Steve into Captain America; when Tony mentioned how his parents always seemed to make their relationship work, Steve says he only knew Howard when he was young and single.

“Oh really? You two knew each other?” Tony replies. “He never mentioned that. Maybe only a thousand times. God, I hated you.”

On the DVD commentary, McFeely says that this scene, and the long history of Cap and the Starks, was carefully planted not only in past films, but also in the spinoff series Agent Carter, about the post-WWII adventures of secret agent Peggy Carter (Hayley Atwell). As McFeely puts it:

We were doing Agent Carter — this is a very small aside — but we wanted to make sure in the final episode of Season 1 of Agent Carter that Howard says something to the effect of ‘Steve Rogers is the greatest thing I ever did.’ Just so, for anybody who’s listening, it would pay off this idea that maybe he would pursue Super-Soldier Serum all the way into the ’90s.

The scene he’s referring to comes near the end of the last episode of Agent Carter Season 1. Peggy has to talk a hypnotized Howard Stark (Dominic Cooper) out of dumping a chemical weapon on New York City. As she pleads with him over a radio (an echo of the end of the first Captain America movie), Stark says:

All I’ve done my whole life is create destruction. Project Rebirth was ... [Steve] was the one thing I’ve done that brought good into this world.

And it all connects; when Howard Stark is killed in flashback at the start of Civil War, he’s carrying a trunk full of Super-Soldier Serum. And though it’s not explicitly stated in this scene from Agent Carter, McFeely and Markus note the potential for jealousy when a man thinks the greatest thing he ever created was a soldier and not his own son.

“See?” they quip. “There is connection between the television-verse and the movies.”

For Marvel zombies, this might not be as satisfying a crossover as seeing Daredevil show up in Civil War’s airport scene, but it’s still a really smart character detail, showing how, while Steve and Tony might be friends now (or were until the end of Civil War), there was friction between them before they ever met. And Howard’s death at the hands of Bucky (which Cap knows, or at least suspects, and doesn’t reveal to Tony) is the final straw in their conflict. The scene in Agent Carter probably raised very few eyebrows on its first airing. In retrospect, it’s some of the finest foreshadowing in Marvel’s Cinematic Universe to date.