Despite their characters not getting along for the majority of the film, off-camera Jean Louisa Kelly got along very well with John Candy and said she was honored to work with someone she considered a legend.
Laurie Metcalf who plays the lonely neighbor lady recalled how nervous she was on this film, given she didn't have a lot of film experience at the time. More so as she was working with John Candy as he was a pro at improv. But Metcalf saw those fears pass when she felt that Candy sensed her nervousness and proved to be a supportive and generous scene partner. Metcalf said that Candy was good at reading people and wanted to put her at ease.
One night during filming, John Candy went to a bar with Music Supervisor Tarquin Gotch, and spent most of the night there meeting people. The next day, John Hughes heard a caller on a radio talk show excitedly describe his evening with Candy. Hughes was upset with Candy, and despite Candy's assertion that Buck was supposed to appear disheveled, Hughes cancelled his scenes for the day, and told him to get himself together and get some sleep.
Almost every set was built in a local high school gymnasium, including the two-story Russell house.
The movie was originally intended to be shot in the St. Louis area, rather than John Hughes' traditional Chicago. Filming was about to begin when the decision was made to move the shoot to Chicago. The film was set in winter, and the winter of 1988 was unseasonably warm in St. Louis, leading to the change.