Continuity mistake: When Jenny, David, Danny and Helen are driving up to the house that's for sale that David and Danny want to look at, Carey Mulligan & Dominic Cooper are in different seats in different shots. In the first shot, the camera is in the backseat, and shows Peter Sarsgard driving, and Dominic Cooper in the front passenger seat. When the car pulls up and parks, Carey Mulligan is in the front passenger seat, and Dominic Cooper is behind her in the back seat. (00:44:10)
Factual error: Above their bed in the French hotel is a photo of a Boeing 747 which didn't fly for the first time until 1969, after the setting of this movie.
Other mistake: In the scene where Jenny waits in the car outside an apartment building while David helps a family move into their flat, an older woman looks out of the window of her flat. We see her reflection in the window of the car Jenny waits in. However, the car is standing beyond the corner of the building - there are no windows that could possibly reflect in the car's window.
Continuity mistake: In the very early scene in which Peter Saarsgaard gives the girl a lift because it is raining, he puts her cello into the rear seat (via the offside door) neck first. A few minutes later, when she retrieves the cello from the back near-side door, it comes out base first.
Factual error: Jenny would not have received a letter telling her she had been successful in applying to Oxford University as shown at the end of the film. As an undergraduate she would have received a letter from one of the Oxford colleges to which she had applied informing her she had been accepted to that college.