Factual error: In the second last scene, when Rachel is leaving Singapore for New York, Nick went onboard to propose, and convinced her to stay in Singapore for one more night. However, that's not possible in Singapore as there are strict laws stating that those that enter the departure area must have a boarding pass, with the purpose of leaving the country. Those that have a boarding pass but have no intention to depart the country will be prosecuted, and in 2018 40 people were arrested for various reasons, such as sending a friend off and meeting their idols, etc.
Continuity mistake: When Nick and Rachel board the flight from New York and are sitting in their 1st Class pod, they are sitting talking before take off and Rachel has painted nails, but when they arrive in Singapore she does not.
Factual error: When Nick is talking to his mother at the beginning of the film, he is in New York City and she is in Singapore. It is just after lunch in NYC. The time is 13 hours ahead in Singapore but it is somehow bright daylight and obviously the middle of the day.