The 33-year-old actress stars as the troubled alcoholic protagonist in the upcoming mystery thriller and little Hazel accidentally saw a part of the trailer, reported Female First.
"When I came home from work, she said, 'I don't want to see mommy on the screen anymore'. I was like, 'Oh, great, that's it for acting!'
"I just explained there's sometimes there's 'screen mommy' and sometimes there's 'real mommy.' But how do you explain this job when it's so bizarre?" Blunt said.
"Well, my girls can't see ('The Girl on the Train') , can they? So I have to do a couple they can see. When I, hopefully, proved I'm not an unfit mother.
"I would have done 'Mary Poppins' whether I had children or not, but the fact that I have girls makes it such a gift," she said.