Other mistake: When Charlotte stubs her toe there are numerous shots of her walking normally in bare feet and sitting by the window there is a close up of her feet, for one her toes look fine, and if she had damaged the middle toe on her foot to extent it needed hospital treatment she would have had some trouble walking about normally. Even if she hadn't broken it, the doctor did put a support onto it suggesting it was hurt enough to warrant that. (00:39:40)
Other mistake: When Bob wakes up after the night with the singer she is already in the bathroom. However, the pillows on her side are obviously untouched. (01:19:20)
Answer: I believe that it means something like "good luck", as she hoped the production goes as smoothly as possible.