Continuity mistake: When Charlotte leaves Will's apartment in the white gown he has given her, she is wearing a pair of white high heels. Later, at the party, they're dancing and she is wearing white platform sandals. The next morning, when she wakes up in his apartment and her clothing is strewn all over the floor, the original shoes are seen again.
Continuity mistake: When Dr. Tom Grandy is flying in the helicopter, looking over Charlotte's files so that he can operate, what he's actually looking at are the diagnosis sheets found in any emergency room. They're just lists of injuries, diseases, etc.
Factual error: During the multiple hospital scenes, the doctors direct their updates to Will, ignoring the closest family member, her grandmother. Will's relationship with Charlotte is not even a year old. No hospitals or doctors would ever discuss this condition with anyone outside the immediate family, including and especially the Cleveland Clinic.