6. There's A Loaded Call-Back To Raza
In the original Iron Man, we met the Ten Rings as led by Raza, the terrorist who ends up having his face deformed by an explosion caused by Tony Stark's escape in the first Iron Man suit.
The actor who played him - Faran Tahir - actually talked about the possibility of Raza returning in future Iron Man movies and that led to some suggesting that he would be playing the Mandarin eventually. Tahir was actually quoted as saying he had discussed returning:
"We’re still talking about it. It hasn’t been finalized yet, so we’ll see. The character didn’t die in the first one, and it is part of a larger story. Iron Man’s biggest nemesis is Mandarin, and my character is the only reference to Mandarin. So we’re still trying to figure out how it’s going to fit. The things to consider, I think, are that if it is a bigger story, how much of it is exposed [and] when."
"Is he the conduit to Mandarin? Does he become Mandarin? Is it just another leader of the Ten Rings, you know, thing? All the allusions [in] my first speech was all about Genghis Khan and all that, which is Mandarin’s thing, you know? So I think they have created the character and the storyline very wisely. To leave it as open as possible so whatever they need to, you know, pull from, they will."
Ultimately, Ben Kingsley played the stand-in for the Mandarin (though it was revealed that the real Mandarin is still out there), but as a nod to Raza being the first leader of the Ten Rings, Kingsley's version wears the ring Raza wore in the first movie as one of his ten rings...