Jon Hamm Explains Injuries From 'Mad Men' Set (Video)

“Mad Men”

Jon Hamm

Advertising titan Don Draper may seem like he lives a calm and collected life at the Mad Men offices, but behind the scenes it's a battlefield for actor Jon Hamm

The star of AMC drama dropped by the Late Show with David Letterman Thursday night, promoting his new film, Friends with Kids, and revealed the injuries he's amassed on set.

"It's an office show, so we don't have a lot of stunt work," Hamm explained to Letterman.

"I remember writing down the injuries I've had on the show," -- an insurance formality, he says -- "and the lady goes, 'You broke your hand, you had eight stitches in your head, you separated your shoulder... all of this happened on the set of Mad Men?'"

As Hamm describes it, he broke his hand while rehearsing a flashback to a scene in the war in the first season. "There was an explosion and I'm supposed to look like an awesome, cool dude diving out of the way," he says. "They've thoughtfully set out a pad for me to land on. So we rehearse it, and I run and I jump and I land on the pad, and my hand catches, and I hear a very audible snap. And that was the rehearsal."

Audiences never noticed Hamm's broken hand thanks to a removable cast. But the actor encouraged fans to watch the DVDs closely. "I have this bear claw swollen hand," he joked. "It looks ridiculous, like it's been over-inflated."

The separated shoulder was a direct result of the broken hand, unfortunately. When the series ultimately filmed Draper's war flashback scene, Hamm said, "I couldn't land on my hand because it was broken, so I had to land awkwardly... and separated my shoulder."

As for the stitches, Hamm says a piece of the set fell and hit him directly on the head. "Eight stitches, blood down the neck," Hamm explained. "I immediately took my jacket off, because it's rented."

"Oh buddy," Letterman said. "Now I see why you were able to buy the Dodgers. That's a golden ticket."

Mad Men returns to AMC for it's fifth season March 25.