Steven Spielberg was the executive producer of the film, the first to be made by his production company, Amblin Entertainment. Lead actor John Belushi and Spielberg previously collaborated on 1941 (1979).
Nell is chopping wood as Ernie approaches. As they begin to talk Nell piles wood in her cradled left arm. The next shot is closer and at a different angle. As this shot begins Nell has no wood and begins to pile it once again in her cradled left arm.
When the apartment blows up the headline on Souchak's column is "Room Wanted - Quiet Tenant," while later, when Nell is looking through Ernie's Rolodex of saved columns the headline is "Apartment Wanted - Quiet Tenant."
When Souchak rides the Empire Builder back to Wyoming with Nell, the train takes a route the Empire Builder never takes. In the movie, the train goes through Cedar Rapids, Iowa, and then on to Victor, Wyoming, where they get off. The real Empire Builder goes north from Chicago to Milwaukee and then Minneapolis before heading northwest and crossing North Dakota, Montana and Idaho near the Canadian border. It goes nowhere near Iowa or Wyoming.