Iron Man hidden details: easter eggs and behind-the-scenes facts

Captain America's shield in the workshop

In the scenes where Tony builds his suits, a partly finished Captain America shield sits on a workbench. Favreau has said an artist at Industrial Light and Magic slipped it in as a joke for the filmmakers' review sessions, and it stayed. Iron Man 2 later paid it off by having Tony use a shield to prop up equipment.

The improvised ending

The script was unfinished when filming began, so much of the dialogue was worked out on set. Jeff Bridges called the production a $200 million student film. Gwyneth Paltrow was less comfortable improvising, so Favreau noted her off-the-cuff remarks and wrote them into her lines.

Robert Downey Jr. improvised the film's final line, "I am Iron Man", in which Tony admits his secret identity at a press conference. Marvel's Kevin Feige felt it suited the character. It broke the superhero convention of a secret identity, and the Marvel films built on it for years.

Cameos and set-ups

Several small moments planted much larger stories.

• Stan Lee appears at a party, where Tony mistakes him for Hugh Hefner
• Clark Gregg makes his first appearance as Agent Phil Coulson of S.H.I.E.L.D., a character who went on to appear across the Marvel films and television
• Terrence Howard, the first actor cast, plays Rhodey, and Favreau reportedly chose him partly so he could become War Machine in a sequel; Don Cheadle took over the role in Iron Man 2
• Jeff Bridges shaved his head to play Obadiah Stane, who replaced the Mandarin as the villain after Bridges was cast

The Nick Fury post-credits scene

After the credits, Samuel L. Jackson's Nick Fury waits in Tony's house to talk about the Avengers Initiative. Favreau has said the scene was not in the original script and was meant as a fun easter egg for comic fans. He also said he and Feige chose Fury's words carefully. That short scene became the template for Marvel's post-credits teases.

Production facts most fans miss

Favreau cast Robert Downey Jr. over objections from Marvel executives, and Downey was paid $500,000 for the role. The origin was moved from the Vietnam War to Afghanistan so the story would not be a period piece. The Afghanistan scenes were shot in California, including Lone Pine, the Olancha Sand Dunes and Edwards Air Force Base.

Filming ran from March to June 2007 on a production budget of around $150 million. Many of Stane's scenes were cut so the film could stay focused on Tony.

Iron Man hidden details that shaped Marvel

Several of these small touches became the foundation of a franchise. Coulson's appearance, the shield on the workbench and the Nick Fury scene all pointed to a shared universe before Marvel had committed to one. Downey's improvised final line also set the tone for how Tony Stark would be written for the next decade.

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