Factual error: The old man is supposed to have accidentally ended up at Rita and Peter's wedding by just "getting on a train," and finding himself in Lake Forest (a far northern suburb of Chicago.) But he started out in Berwyn (a western suburb), and in order to get to Lake Forest from Berwyn, you have to get on one train, get off in downtown Chicago, walk several blocks, and then get on an entirely different line going to Lake Forest. In other words, not something you can "accidentally" find yourself doing, but something you have to know where you are going in order to do.
Peter Hoskins: What goes into one, Rita? A Long Island Iced Tea?
Rita Boyle: I'm sorry darling, I've forgotten.
Peter Hoskins: What, do you have it all written down behind the bar or something?
Rita Boyle: I'm on vacation.
Peter Hoskins: So you can't remember a drink recipe for something that I would like to order?
Rita Boyle: Peter, you're doing it again. You take a perfect situation and you pee all over it.