Factual error: When Renee Zellwegger arrives in New York, she exits her cab in front of the United Nations. The Canadian flag is visible. The movie is set in 1962, and the form of Canadian Flag in the shot was not adopted until 1965.
Factual error: At the end of the movie mention is made that Catcher gave Barbara his publisher's Celestron telescope, shown earlier in a scene where the two are looking at the moon. This was probably product placement, but the C10 design shown in the movie was not offered by Celestron until 1964 (the film is set in 1962) and it sold for a price of around $2000, not $6000 as stated in the movie.