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.
Continuity mistake: During Nash's first lecture at Wheeler Labs, he writes a mathematical problem on the blackboard. However, you can see that the dimensions of spaces change between shots - first there is R^3, then R, and finally R^3 again.
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.
Continuity mistake: During their first date, Nash and his date have a brief conversation where they have stopped walking after she makes the comment about God must be a painter. As the shot changes from each of their angles, the distance between the two changes each time. (01:04:10)
Continuity mistake: In the car chase at the dockside the car Nash is in screeches to a halt, veering slightly to the left. When they get out the car wheels are pointing to the right. (01:16:00)
Answer: You do not specify to which scene you are referring. The only window I recall with writing on it would be the window in Nash's room. John had covered this window in mathematical equations, theorems and geometric patterns. While most of the symbols used are Greek in origin, the language is simply that of mathematics.
Michael Albert