Factual error: When John Cusack puts Springsteen on his LP-player, he places the needle at the start of the record. The song that plays is the studio version of "The River." Therefore, the album has to be "The River," which is a double album, but "The River" is not at the start of either of the two LPs, but is the last song on LP #1. (00:18:10)
Factual error: When Rob visits Charlie, it's clear, from everything to her clothes to her home decor to the design of her loft, that Charlie is a wealthy person who lives in a fancy apartment. It's also clear that she's very snobby and shallow. Yet when Rob leaves from his evening at Charlie's, the address shown is in the middle of a very rundown and rather isolated neighborhood that in 2000 (when the film was made and set) was poor, somewhat crime-ridden, and years away from being anywhere someone like Charlie would have been caught dead in. Not only that, but the type of building is not to be found in that neighborhood anyway.
Factual error: When Rob is going through the mail in the lobby of his apartment, he picks up an envelope which has an address listed like this: 12345 Street, Chicago, Illinois. (I forget the name of the street.) However, in Chicago, that mail would never have actually been delivered anywhere: all the street addresses within the city of Chicago are specified as to whether the street is North, South, East, or West - an address that didn't specify one of that would have just stayed in the dead letter box at the post office.