6. The rest come together
Amazing as it might seem now, Alan Ruck was not, in fact, the first choice for Cameron.
Nope, Hughes created that part for regular collaborator Anthony Michael Hall.
"John actually had written Ferris Bueller for me. We both determined that I should move on to other things," Hall has since said.
"I needed a break. I wanted to try some new things. So I did Out of Bounds. I can only think back and thank John. He changed my life forever."
Why did Hall decide to pass? Because he'd already played Farmer Ted the Geek in Sixteen Candles, Brian Johnson the nerd in The Breakfast Club and Gary Wallace, another geek in Weird Science, and was genuinely concerned about being typecast.
After Emilio Estevez also passed, 29-year-old Ruck got the role and rest is history, including his improvised voice as Sloane's dad, which was based on a theatre director he and Broderick had acted for.
And if you thought Hughes went through a long list to find Ferris, that's nothing compared to the phone book-sized set of candidates for his sister Jeannie.
The likes of Ellen Barkin, Kim Basinger, Carrie Fisher, Melanie Griffith, Linda Hamilton, Daryl Hannah, Holly Hunter, Kelly LeBrock, Anjelica Huston, Julia Louis-Dreyfus, Michelle Pfeiffer, Sigourney Weaver and Debra Winger all tried out for the part.
Ironically, Ferris' sis ended up played by Jennifer Grey, who was dating her on-screen brother during, and for a short time after, production.
It was Grey's suggestion that led to one of the best moments in the movie - Charlie Sheen's drug addled loser - since she'd enjoyed working with him on Red Dawn.
With real thesping commitment (or just his thanks to his hard-partying style) he stayed up for 48 hours to get the desired dopey effect.
Mia Sara was a fairly easy choice, but the character's name has more of a history - she was named for then-head of Paramount Ned Tanen's daughter.
Finally, there's Ben Stein, who actually does hold a degree in economics and was asked by Hughes to recite an actual lecture. The scene is entirely unscripted aside from the "Bueller... Bueller" moment at the start.
Now he had a cast in place, Hughes could shoot...
Next: The production