The studio famously didn’t want Robert Downey, Jr. for the role, but relented once they realized he was a perfect fit. But, during the development process, everyone from Tom Cruise, Nicolas Cage and Timothy Olyphant all auditioned for the role. Crusie was arguably the closest, and was even attached to potentially co-produce at one point.
It was no coincidence that Marvel used Iron Man to kick off their cinematic universe in earnest. A movie based on Tony Stark had been in development since 1990, and it took 17 years to finally happen. Along the way, the project passed through four different studios, all to no avail. Ironically enough, it took Marvel itself to finally make it happen.
The main version of the suit used in the first film reportedly weighed about 90 pounds — which is a pretty massive pile of metal to pile on top of a human. It was apparently pretty arduous, as it had to be worn by stuntmen and Downey, Jr. at times for different shots.
Much of the dialogue was actually ad libbed during the shoot, since the majority of the working script was focused on the action set pieces and overall story. This worked out nicely for Favreau and Downey, Jr., who apparently thrived on the loose filmmaking style. But, Paltrow apparently had a little more trouble, and reportedly had some issues keeping up as Downey, Jr. riffed.
The fan-favorite JARVIS (Just A Rather Very Intelligent System) interface system used in the Iron Man armor was named in honor of Tony Stark’s comic-based butler Edwin Jarvis. The writers were afraid to include the human Jarvis in the script, because it was too close to the Batman/Alfred relationship, so they converted him into a snarky AI.
The production crew snuck in a Space Invaders cameo
You know that sounds that pops up during JARVIS’s target lock? It should sound familiar to classic gamers, because it’s the laser cannon from Space Invaders. As hardcore fans know, classic gaming also gets a little nod in The Avengers, when Stark spots an extra playing Galaga on the bridge of the S.H.I.E.L.D. helicarrier.
Another very early draft apparently featured Howard Stark, Tony's father still very-much alive. In that version of the story he was the main baddie, and became a ruthless version of War Machine. Judging by this, it’s obvious this movie went through some pretty massive changes before it finally happened.
An early draft of the script featured famed Iron Man baddie The Mandarin as the main baddie, though he was re-imagined as an Indonesian terrorist at this point. Favreau didn’t feel it was a good fit, though, calling it too “fantastical,” so he nixed the idea. Of course, The Mandarin is the main enemy in part three, portrayed by Ben Kingsley.
Jon Favreau’s first choice for Pepper Potts was not Gwyneth Paltrow. No, he originally wanted Rachel McAdams, but she turned down the role. Of course, the rest is history, and Paltrow has held the role for more than a few movies.
An early draft of the script allegedly mentioned off-hand that Tony Stark built Doctor Octopus’ robotic tentacles, which were featured in Spider-Man 2 a few years earlier. It makes sense Marvel would want to start planting seeds, but it proved a little too convoluted for the master plan.
Before Jon Favreau took the reins, there were a lot of guys on the short list to make this movie. Quentin Tarantino, Joss Whedon, Len Wiseman and Nick Cassavetes were all approached to direct the film before Favreau signed on. Tarantino would’ve been cool, and it seems Whedon almost got started in the Marvel universe a little earlier.