(at around 34 mins) When Maya, Tony, and Pepper are discussing the huge stuffed bunny in the living room, Tony has hung a stocking for J.A.R.V.I.S. The stocking was the same colors as Vision (red, green, and yellow), the android, into which Tony and Bruce turn J.A.R.V.I.S., in Avengers: L'ère d'Ultron (2015).
This is the first movie in the Iron Man franchise not to be directed by Jon Favreau, possibly over creative differences with Marvel or because of his salary demands. He later said that not directing allowed him to have more fun with his character "Happy" Hogan, saying that he was like "a proud grandfather, who doesn't have to change the nappies, but gets to play with the baby."
The idea that "Happy" Hogan's favorite television show is Downton Abbey (2010) was at the suggestion of Jon Favreau, who is actually a big fan of the British series.
The first Iron Man movie to gross over $1 billion, and the second Marvel movie to reach this mark, with Les Avengers: le film (2012) being the first.
Stan Lee: (at around 1h 3 mins) The Iron Man creator plays the beauty pageant judge. Of the three Iron Man movies, this is the only one in which Lee's cameo does not involve him playing or being mistaken for another celebrity.
Shane Black: [Christmas] Except for the prologue, the whole movie is set at Christmastime. Black's L'arme fatale (1987), Le dernier boy-scout (1991), Souviens-toi Charlie (1996), and Baisers fumants (2005) were also set at Christmastime. Le dernier des héros (1993), which Black did not direct but helped write had at least a partial Christmas setting.