As the flaps were not in take off configuration, Take off warning came on when they pressed the TOGA switches to set take off power . Up to there, just a little crew mistake of having forgotten the flaps. That's why the take off warning is there. But to continue the take off is a foul play!!!
The QAR should have marked that even, and if the Company Flight Safety Officer did his job, they've been invited for "tea and biscuits" if not worse...