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.
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 reason being that the film was set in winter, and the winter of 1988 was unseasonably warm in St. Louis, leading to the change).
Winona Ryder was the first choice for the role of Tia after John Hughes had seen her in Beetlejuice (1988). But Ryder turned it down as she was busy working on Heathers (1988).