Corrected entry: The whole plot line of Rachel getting off the plane is most definitely impossible in post-9/11 America. Regulations consider any passengers that get off the plane after they've boarded to be security risks. When Phoebe gets Rachel talking about something wrong with the plane, causing panic, all those panicked passengers would have been stopped, and Rachel likely would have been questioned for the suspicious nature of that phone conversation. Likewise, when Rachel goes running off the plane, she at best would have been forcibly stopped and questioned, and at worst would have been shot, like the mentally ill guy in Miami in early 2006.
Corrected entry: In the final episode, Monica and Chandler take home the twins almost immediately after Erica has them. No hospital in the United States would ever allow newborn babies to go home the day they are born. Even the most healthy babies are required to stay at least 24 hours at the hospital.