Goofs

At the inauguration party for Rosie's hotel, Ruby is in the frame; 13 seconds later she's running through the front door. This is impossible.

Rosie applies to Boston College but receives an acceptance letter from Boston University, a totally different higher-learning institute.

Alex leaves for the United States to go to Harvard for medical school, but he only just graduated from high school at 18 years old. Unlike in the United Kingdom, medical schools in the United States require a bachelor's degree for admission.

Many of the cars throughout the movie were not yet produced in the year it was meant to be.

Both the Fiat Punto parked near Rosie's house and the Mercedes at the hotel have the same VX02... number plate (possibly identical) despite it being pre-2002.

When Rosie leaves the car with Greg for college dance, the audio of Alex saying "Wanker!" precedes the video.

When Alex takes Rosie to his Boston apartment for dinner, his "American" girlfriend (played by English actress Tamsin Egerton) explains the menu for the evening. She states that the entrée is finished with rocket sauce. Rocket is the British term. An American like Sally would call it arugula.

Sally and Alex have cake with white wine while it's dark outside. Then Alex exchanges text messages with Rosie, who's on the beach during daytime. Either Rosie is on the beach very early and Sally and Alex had a very late dinner, or Sally and Alex are having wine and cake for breakfast, or someone ignored that Boston is 5 hours *behind* the UK, not *ahead* of it.