At the end of the theatrical trailer, there is an outtake of Walter Matthau in the bath tub saying directly into the camera "If I'd known there was going to be a nude scene, I would've asked for an extra million." The crew found this so hilarious, they ended up using it as a post credits scene.
The sixth pairing out of ten movies of comic actors and great friends Jack Lemmon and Walter Matthau.
After filming this movie in Minnesota in freezing temperatures, Walter Matthau was hospitalized with double pneumonia.
Jack Lemmon and Walter Matthau did not think that this movie would be anything special, and were surprised that it became a box office success on a budget of around $35 million, and making $70 million.
When Gustafson wakes up from Ariel knocking at the door, in the middle of the night, he mumbles "Vad är det?" - Swedish for "What is it?"