Near the end, where Nick Fury and Tony Stark are talking about the Avengers, there is a world map behind them featuring dots. The dots show where the Avengers are: New York (Iron Man); Arctic Circle (Captain America); Europe (Black Widow); Lower Africa (Wakanda for Black Panther); California (Hulk); New Mexico (Thor); Southern Atlantic Ocean (Namor the Sub-Mariner).
The late DJ Adam Goldstein appears as himself in the movie during Stark's party. The film is dedicated to his memory.
The suits were much lighter than the ones used in the first movie, and the legs were left off. From the thighs down the actors were covered in digital markers and the bottom part of the suits were later added with CGI. (As stated in Popular Science, June 2010.)
Emily Blunt was originally cast as Black Widow, but scheduling conflicts with Gulliver's Travels caused her to pull out.
Spoiler: The film closely resembles several key Iron Man stories from the comics. The part when he was drunk references the "Demon in a bottle" storyline, where Rhodey dons an Iron Man suit. The part of him dying is somewhat similar to "Ultimate Iron Man." Also, the idea that his technology is used in a way he doesn't like and having a battle is similar to the "Armor Wars" plot.
Attack of the Show host Olivia Munn mentioned she was to have another role in the movie. She played reporter Chess Roberts, but originally had a somewhat bigger role. She was to play a girl at Stark's birthday party who then appears in his bedroom. The scene was eventually cut because it didn't have any comedy in it.
Stan Lee makes his customary cameo. He is mistakenly introduced to Tony during the Expo as Larry King.
In the comics, Justin Hammer is an elderly man whose appearance is based on actor Peter Cushing and who is named for the Hammer Horror films in which Cushing appeared.