With more than 20 films in its catalog and several billion dollars reaped from the global box office, the Marvel Cinematic Universe is a Hollywood juggernaut. It stands to reason that a franchise this successful must have cracked the script-writing code, delivering laugh-out-loud dialogue and memorable moments with machine-like precision. Yet, with all due credit to the MCU's screenwriters, some of the series' most standout bits of dialogue never appeared in any screenplay.
Over the years, various film commentaries, interviews, books, and special features have revealed a surprising number of unscripted Marvel moments. Sometimes these improvised Marvel scenes were created the day of filming by the actors and directors; other times, actors couldn't help tossing in an extra bit of business while filming a scene. These are the funniest, silliest, and most charming improvised lines in Marvel movies.
In the original Iron Man comics, Tony Stark spent several years pretending the "Iron Man" was actually his personal bodyguard. This is the story that S.H.I.E.L.D. cooks up for Tony at the end of the Iron Man film, but the billionaire playboy philanthropist just can't help himself from taking the credit. It's a move that feels entirely true to the character, and "I am Iron Man" became a pivotal moment for the MCU.
According to Marvel Studios head and Iron Man producer Kevin Feige, the line was ad-libbed by Robert Downey Jr., and Feige liked the change so much that he rolled with it. "It’s a fine line," Feige told IndieWire, adding:
If you're changing something for no reason, that’s one thing, but if you're changing something because you want to double-down on the spirit of who the character is? That's a change we'll make. Tony Stark not reading off the card and not sticking with the fixed story? Him just blurting out "I am Iron Man"? That seems very much in keeping with who that character is.
While Peter Parker turning to ash before Tony Stark's eyes was always part of Avengers: Infinity War, the touching words he utters to "Mr. Stark" as he disappears are 100% Tom Holland.
During a Q&A at Iowa City High School, Infinity War co-director Joe Russo said the direction given to Tom Holland was something to the effect of, "Act like you don't want to go." This led to Peter's ominous "I don't feel so good, Mr. Stark," and his repeated plea of "I don't want to go."
This improvisation was also confirmed by screenwriters Christopher Markus and Stephen McFeely.
While attempting to escape Sakaar, foster brothers Thor (Chris Hemsworth) and Loki (Tom Hiddleston) discuss how they might get past the guards. Thor gleefully suggests a maneuver called "get help," which Loki flatly refuses. Smash cut to Thor carrying Loki and screaming, "Get help!" before throwing his brother at the nearest guard.
According to Hiddleston, this sequence was conceived the day it was filmed. "We literally just came up with it on the day," the actor told attendees of the 2018 ACE Comic Con. Hiddleston added that it's not just a funny bit but also a touching glimpse into the characters' relationship:
This idea that this is a trick that Thor and Loki used to... use it as a game when they were kids and they stopped doing it a long time ago but it used to work and it might just work this time. They got one last ace up their sleeve. And the idea that Loki hated it, and just was like, "I don’t want to do it. It’s humiliating." And that Thor was like, "You’re going to love it! Come on!" in a big brother way. And then it works. In that moment, I always love the fact that it wasn't just a funny moment, but actually, you understand something deeper about them as brothers, and I think those moments are really special.
During Infinity War's standoff between Iron Man and the Guardians of the Galaxy, Star-Lord demands to know where Gamora is, unaware that Tony Stark has no idea who he's talking about. According to screenwriters Christopher Markus and Stephen McFeely, the exchange between Chris Pratt and Robert Downey Jr.'s characters was in the script, but Drax's existential follow-up was an ad-lib by actor Dave Bautista.
In an interview with Yahoo!, Markus explained, "The script only said, 'Where is Gamora?' 'I'll do you even better: Who is Gamora?' And then one day Bautista just goes, 'I'll do you one better: Why is Gamora?' It's like, 'OK, you're very good at your job.'"