Factual error: I live in Chicago, and live near where they filmed the outside shots. Every time we see Mel coming out of his apartment, the address says 2400 Lakeview Drive. However, anyone who lives by here knows that this particular building has no balconies, and Mel repeatedly went out, or looked over his balcony.
Factual error: When Nick is in the psychiatrist's office and tells her he can read women's minds, Bette Midler's character says, "Sigmund Freud spent his entire life trying to understand what women want," or something to that effect. Actually, Freud didn't care much about the psychology of women, he simply passed them off as having "penis envy". Most psychologists today recognize that Freud was a little off base. It seems like the writers just used Freud's name because he's the only psychologist the general public would know by name.