Factual error: In a scene that takes place in 1956 or 1957, Alicia Nash places an orange Tupperware container in the refrigerator. Although Tupperware first became very popular in the mid-50s, the particular model of Tupperware used in the film was not introduced until the late 60s or early 70s.
Factual error: At the Nobel Prize Ceremony, Nash is giving a speech. During a wide-shot right before he leaves the stage, you can see a few girls wearing white military style caps (to the right of the screen). Hats are in fact worn by Swedish students at the Nobel Prize Ceremony, however the style is completely different. The caps should have a much smaller, soft crown and not the wide crown of a military hat.
Factual error: John Nash enters Princeton as a graduate student (Ph.D.) candidate in 1947. By that time the Graduate College had already been built (1913) and is about three miles from the main campus. At that time, all graduate students had to live at the Graduate College building, and not where Nash is shown living with his imaginary roommate at the center of campus.