- Stealing a pregnant woman’s pee is fine if you want to fake a home-pregnancy test and fool your husband, but it would never fool an actual doctor. This is the 21st century and they no longer kill a rabbit. Your doctor instantly gives you a full physical, including a blood test that tell them a lot more than pee ever could.
- Likewise, you can’t secretly impregnate yourself with one specimen of frozen sperm. You’d have two options: Either do IVF, which is a long complicated surgical procedure with a high fail rate (but at least you get several shots off one sample) or you can attempt to self-thaw and then use the turkey baster method, which would have an astronomically high fail rate, and you’d only get one chance. Getting pregnant even with a fully-participating man is already quite unlikely on one try.
- Why does Nick stay with her for five weeks (it was longer in the book, iirc) after she comes home and before he finds out she’s pregnant? In the movie, she says that otherwise the press will turn on him, so he has to stay, but so what? Before, he was trying to win the press over to avoid being arrested, but why would he care now? It makes no sense. Of course, the real reason that he has to stay so long without a good motivation is to allow time for the impregnation storyline.
If she’s so dedicated to her long-term revenge plan, then secretly going off the pill for a few months would not be so much of a stretch. This would give her enough chances to actually get pregnant, and allow her to actually prove her pregnancy to a doctor.
In this version, she would enact her revenge long before her pregnancy showed, planning to abort the baby sometime later (or not, if we’re going with the kill herself version, which would also require an actual pregnancy). She could leave a clue for Nick in the woodshed that implies she aborted the baby, then reveal to Nick at the end that she never got around to it, which still allows you to have the shock-ending. This would also help explain Amy’s sudden change-of-heart and desire to return to Nick: Pregnancy is a hormonal roller-coaster, after all, and it tends to reset your priorities.
And, most importantly, in this version, she could confront him the night of her return, or at least that week, rather than forcing him to stay in the house with a psychopath for no reason whatsoever.
Why didn’t they do this simple fix? Because murder and rape are sexy and fun, but pregnancy is a turn-off and abortion is beyond the pale? Ugh. If Flynn was going to go there, she should have went there, and solved three huge problems with one quick fix.