Speaking to Claudia Winkleman alongside partner Katya Jones during Saturday's show, Harman revealed all as he clutched onto his ribs.
Explaining what caused the injury, Harman told Winkleman: "I was leaping off a rostrum and was about to be caught by some very handsome men and as I flew I was Peter Pan but when I landed I was in A&E.
"I've done something to my rib basically, and it's quite painful and I'm a little bit high on painkillers as well but I'm having a lovely time."
Harman and Jones shared a chuckle before Harman continued: "I've loved it and I am loving it, it's too soon to say loved.
"This hasn't really sunk in...I've been avoiding Kat all day because that makes it really real."