The Husband's Death
Because Kyle told Julia that her dad would be in New York with her when she woke up (when the plane landed), I assume Kyle didn't tell Julia that her dad died.
Early in the movie, Kyle tells the flight crew that her husband has been dead for six days.
I know Julia probably wouldn't understand death because she's only six, but wouldn't she have noticed her dad's absence and asked Kyle about it?
~Vivian