Jill and Tom Garvey greet each other in the diner by saying "Looking good, Billy Ray!" followed by "Feeling good, Louis!" These are the last lines of Trading Places (1983) between the characters of Dan Aykroyd and Eddie Murphy.
The title refers to MIT scientists wanting to buy Nora's house for $2.1 million. They are intrigued by the fact that three of her family disappeared from the dining table whilst she was in the same room and didn't disappear. So the reason why she was left behind is a matter of geography.
The Garveys' house number is 420.
The church's street number is 721.