If you look at Jane's phone book, you can see that Lester's work number is 555-0195. This is the same phone number displayed on her mother's real estate sign as *her* work number.
Unrelated, but I just LOVE that scene in The Simpsons where they have a criminal on the phone and they're trying to trace the number. He hangs up and Chief Wiggum says: "Did you get it boys?" When the number is read back it's "555-1 . . . Naw, that's gotta be fake!" and they throw it out.
In Jane's book, the numbers are:
Mom at work 312 555-0281
mom's cel 555-0859
Dad work 312 555-1(either an 8 or 3, hard to tell)51
NOT 555-0195, not even close. You can check this if your DVD player has the zoom feature
BTW here is the time code: Title:1 Chapter:5 hr:0 m:22 s:29
Whether this is true or not I don't actually know, BUT, if it is true it just shows how distant Jane is from her parents, that is...she doesn't even know the real number of her Dad's work. The movie director may have done this on purpose. My advice...look at the context of the mistake and you may find it's not a mistake at all!