Right before shooting a scene in which the group runs through a dirty, trash-filled alley, the Toronto Sanitation department came by and cleaned it up, so the crew had to dig through local dumpsters for more trash.
One of the movie's producers is Debra Hill, who teamed up with John Carpenter to make Halloween (1978), a horror movie about murdered babysitters. Listen carefully when Sara and Kris watch television. The music you can hear is John Carpenter's chilling Halloween (1978) theme, an in-joke.
An early draft of the script has the part of Dawson, the garage owner, played by an extremely unfeminine woman and the scene emphasizes the humor of Sara and Brad's confusion over Dawson's gender. This part ultimately went to Vincent D'Onofrio and the scene as it appears in the film plays with Sara's fascination with the comic book hero Thor and has her confusing Dawson with her comic book hero (to Sara he's cleverly disguised as an everyday garage mechanic).
In an early draft (third rewrite) of the script, there is no mention of Sara's fascination with Thor. What is included instead is a funny scene at Soldier Field with The Chicago Bears Players stars Jim McMahon, Walter Payton, William Perry (William "The Refrigerator" Perry) and Mike Singletary. The boys invite the team members to come to the Anderson House to watch The Mummy's Curse (1944) and when they finally leave, Daryl smuggles out several of the team's jockstraps as souvenirs. The jockstraps later are used to make up the shortage of cash needed to get the station wagon out of (Miss) Dawson's garage. None of the Chicago Bears appear in and only one brief reference is made to the team in the film (by the girl at the frat party).
The two rival gangs on the El Train challenge each other to a fight when the train crosses "Devereux" street, an in-joke towards director Chris Columbus' wife Monica Devereux and father in law Clarke Devereux who both appear in the movie.
When the kids are at the chop shop, Bleak refers to them as the Brady Bunch. In the following scene, when Brenda is still at the bus station, on one of the portable TVs, the theme music from The Brady Bunch (1969) can be heard.
The project started in the 1960s, but was abandoned in the 1970s. However, in the mid-1980s, Chris Columbus finally restarted the project. In the original plot, Jane Fonda was considered to play the lead role. However, Jane was too old for the character and the part moved to Bridget Fonda. But Bridget also withdrew from the project before auditions began.
Steven Spielberg considered being the executive producer of this film and have the film released under the Amblin banner, to help his friend Chris Columbus get the directing job. However Columbus had the directing job secured.