I did some research and discovered that she had a big bruise (!) on her arm when she went on the Craig Ferguson show April 25 while in the US:
And, asked by the chat show host how she had acquired the bruise, Gillan replied that she had taken a tumble while stepping out in sky-high heels.
She said: 'I was really hoping you wouldn't notice! I was trying to be cool in New York, because we were just there promoting Dr. Who and I fell over - right over, it was so dramatic.'
Asked by Ferguson whether she was drunk at the time, she laughed: "No, I wasn't - I promise. That's the saddest part about it. I was wearing big heels and I just went right over.'
Read more: http://www.dailymail.co.uk/tvshowbiz/article-1380025/Doctor-Who-star-Karen-Gillan-tries-cover-huge-bruise-make-taking-tumble-big-heels.html