Unsurprisingly, the full-throttle promotional push for Marvel's The Avengers has made its way to Disney-owned ABC, infiltrating the closing credits of this week's episode of Castle. The 30-second promo, which you can watch below, features Robert Downey Jr. and Nathan Fillion comparing their Tony Stark and Richard Castle characters, an exchange abruptly ended by Downey's declaration that, "I'm Iron Man ... and you're not."

The spot is made even more clever if you recall that the Castle star was long-rumored to play Ant-Man in The Avengers, culminating in director Joss Whedon's joking, and widely misinterpreted, announcement at Comic-Con International 2010 that, “Nathan Fillion is Ant-Man. ... Unfortunately Ant-Man isn’t really in the movie.”

Opening May 4, The Avengers stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as the Incredible Hulk, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Samuel L. Jackson as Nick Fury, Tom Hiddleston as Loki, Clark Gregg as S.H.I.E.L.D. Agent Phil Coulson, Cobie Smulders as S.H.I.E.L.D. Agent Maria Hill and Stellan Skarsgård as Dr. Selvig.

Marvel Studios presents in association with Paramount Pictures Marvel’s The Avengers — the Super Hero team up of a lifetime, featuring iconic Marvel Super Heroes Iron Man, The Incredible Hulk, Thor, Captain America, Hawkeye and Black Widow. When an unexpected enemy emerges that threatens global safety and security, Nick Fury, Director of the international peacekeeping agency known as S.H.I.E.L.D., finds himself in need of a team to pull the world back from the brink of disaster. Spanning the globe, a daring recruitment effort begins.