Corrected entry: The typewriter Jake is typing on near the end of the movie is a small IBM Selectric, a different model than the one seen earlier in the film.
Corrected entry: At the barbeque, when the parents pester the couple about having children, Christie's father tells them how she was born breech. Later in the movie, Christie has her baby and and it is also breech. The problem is that the doctors don't know until the last second. Wouldn't they have had a sonogram months before? Also, the fact that she was born breech indicates that the doctors would have been watching out for that. Babies don't breech themselves at the last second. [I think babies do turn just prior to birth.]