The 28-year-old actress was filming One Day in Scotland when she decided that it would be a good idea to pull her pants down and flash her leading man, not realising that she was being watched by fans with camera phones.
She told the Daily Star, 'I decided to moon Jim after one take, and I thought, 'Oh this will be great' - because he was running towards me and the whole crew was behind me - and I thought that none of the crew will see it and only Jim.
'So I did it and was feeling really good about myself until I realised we were shooting on a street in Scotland and every single resident of the building we were shooting in front of was filming us.
'But the Scots are nice (and haven't posted the footage online)... They have manners and they are discreet. I'm so grateful.'