'Ferris Bueller's Day Off' Turns 30! 5 Things You Never Knew About the Iconic Movie

Think you know everything about Ferris Bueller's Day Off? Think again!

Think you know everything about Ferris Bueller's Day Off? Think again! ET has dug up some little-known facts about the 1986 classic in light of its 30th anniversary this year.

The movie turned star Matthew Broderick into a household name, but the Golden Globe-nominated actor told ET that the film's success came as a total surprise.

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"I loved doing it. It was one of my favorites!" 54-year-old Broderick told ET at The American Side screening earlier this month. "But I didn't know that it was one that would last so long. None of us knew."

Here are five more things that nearly no one knew about the movie.

1. The parade was real. "One weekend was the actual German-American Day parade," Alan Ruck, who played Ferris' best friend Cameron Frye, told ET in a recent sit-down. "What we would do is we'd have Matthew on the float and they'd kind of sneak him into the parade and go down a couple of blocks and then circle around a block and then sneak him back into the parade. And we did that for a whole Saturday."

2. Broderick and co-star Jennifer Grey were dating. Despite playing siblings in the teen comedy, the two actors were an undercover couple during filming. They didn't publicly announce their relationship until later and there was even rumors that they got engaged at some point.

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3. Grey played a hand in Charlie Sheen's casting. "I was helping them cast, and I was in all the casting sessions and I said, 'Would you please use Charlie? He's great,'" Grey told ET in a 1986 interview. "They didn't even audition him. They said, 'OK, we'll take him.'"

4. The Ferrari was a lemon. "They weren't real Ferraris," Ruck revealed to ET. "They were fiberglass bodies over Mustang chassis, and they didn't work right. Pretty much when they sent that thing flying into the ravine, the whole crew was like, 'Yeah!' because it was a tiresome car."

5. It was the anti-Breakfast Club. Ferris Bueller director John Hughes made The Breakfast Club the year before and told ET that he wanted to do a film that was the complete opposite of the dramatic teen flick. "I dealt a lot with the problems of being high school-aged," Hughes shared in 1986. "This is about the undiluted joy of being that age."