Confession time: I saw 'Willy Wonka and the Chocolate Factory' in the theater when I was 4 ... and it scared the daylights out of me. All those horrible things happening to the kids -- especially Augustus Gloop nearly drowning in the chocolate river, then getting trapped in that tube -- haunted my dreams.

As an adult, however, I was able to watch the film again and pick up on its sly humor, particularly Gene Wilder's subtle, mischievous performance, as well as in the film's satire of the adult world as being just as greedy, grasping, and gluttonous as the world of candy-grabbing children. Nowadays, I thoroughly enjoy watching the movie, which wasn't the movie I thought it was at all.

As it turns out, the beloved cult favorite that we've enjoyed for four decades now (it just had its 40th anniversary) isn't the movie any of us thought it was. There are a lot of things people don't know about the familiar film, from its origins as a candy infomercial to its links to 'The Omen,' the 1972 Summer Olympics and the Boston subway system.

Are you ready for a list of 20 things you might now know about 'Willy Wonka and the Chocolate Factory?' As Wilder's candymaker said during Augustus Gloop's ordeal, "The suspense is terrible. I hope it'll last."

1. Watch the opening credits closely, and you'll see that the film's copyright was initially held, not by a Hollywood studio, but by the Quaker Oats company. The cereal maker behind such sweet morning treats as Life and Cap'n Crunch was launching a line of candy bars and had been talking to film and TV producer David L. Wolper about vehicles to promote it.

2. At the same time, director Mel Stuart took up his 10-year-old daughter's suggestion that he approach family friend Wolper in order to make a film of Roald Dahl's children's novel 'Charlie and the Chocolate Factory.' Quaker Oats had never made a movie before, but the company bought the film rights from Dahl and spent nearly $3 million making the movie (a fairly hefty film budget back in 1970).

3. Dahl himself was hired to write the screenplay. Although the finished product bears his sole credit, Stuart actually had the screenplay rewritten by a then-unknown, David Seltzer, who would go on to write 'The Omen' (about the ultimate bratty kid) and 'Lucas' (about a Charlie Bucket-ish underdog, played by the young Corey Haim).

4. Dahl was said to be so unhappy with Seltzer's rewrite (he felt it focused too much on the Wonka character and not enough on Charlie, and that it had sweetened his story's dark tone) that he refused to allow the movie to be remade again in his lifetime or to sell the film rights to the sequel, 'Charlie and the Great Glass Elevator.' (Dahl died in 1990, 15 years before his estate allowed Tim Burton to remake the 1971 film.)

5. Why was the title changed from the book's 'Charlie and the Chocolate Factory' to 'Willy Wonka and the Chocolate Factory'? There are two competing stories. One says that the change was to play up Wonka's name because Quaker's new candy line was called Wonka Bars.

6. The other claim is that the filmmakers worried that the name "Charlie" was seen in some quarters as a derogatory racial term for black people.
The Acid-Trip Boat Ride:

7. Dahl's first choice to play Wonka was wacky British comedian Spike Milligan. His second choice: Ron Moody, who had just starred as Fagin (another dubious role model for naughty children) in the film 'Oliver!'

8. Producers nixed Milligan, and Moody turned them down, as did Jon Pertwee (then committed to TV's 'Doctor Who,' another tale of a mysterious man and a young companion who travel in a magical glass booth).

9. Producers auditioned Joel Grey to play the chocolate mogul but decided he didn't tower over the children enough.

10. Finally, Gene Wilder came along and won the part, which he accepted only on the condition that he be allowed to make his entrance with the fake old-man limping gait that turns into a somersault. "I knew that from then on the audience wouldn't know if I was lying or telling the truth," he recalled in 2005.

11. Ever wonder where the strange middle-European village is that seems to be home to a population of English adults and American kids? It's Munich, where producers filmed because it was cheap and, yes, disorienting. Peter Ostrum, who played Charlie, recalled that a highlight of the five-month shoot in Germany was watching the construction of Munich's Olympiapark, where the Olympics would be held two summers later.

12. Sammy Davis Jr. had wanted to play the candy shop owner who sings the opening song, but producers turned him down. Nonetheless, he made that song, "The Candy Man," part of his act, and in 1972, his version became the only single of his 40-year recording career to hit No. 1 on the Billboard Hot 100.

13. The famed chocolate river, created on a soundstage, was two feet deep and consisted of 150,000 gallons of water mixed with chocolate and cream. The resulting mixture quickly spoiled and filled the soundstage with a foul stench. (Guess I was right to feel bad for Augustus.)

Augustus Gloop and the Chocolate River:

14. Despite Dahl's complaints, the finished film was plenty dark and weird, maybe too much so for small children (hello!) or potential Wonka candy consumers. The movie earned just $4 million at the box office and was widely considered a flop.

15. In the late 1970s, Paramount let its distribution rights expire, and Quaker Oats sold its interest in the film to Warner Bros. for just $500,000. But then, in the 1980s, Warners' repeated licensing of 'Willy Wonka' for TV broadcasts and its release of the movie on home video turned the movie into a profit-making cult hit and allowed Warners to be the studio that ultimately released Burton's 2005 remake.

16. Of the five kids who toured Willy Wonka's factory, only Julie Dawn Cole (who played Veruca Salt) stuck with acting, primarily on British soaps.

Veruca Salt and the Golden Geese

17. Of course, her character was also the inspiration for '90s alt-rock band Veruca Salt.

18. Peter Ostrum gave up acting after 'Willy Wonka,' turning down a three-picture deal. The Cleveland native became a veterinarian and moved to the small farming village of Lowville, N.Y. Preferring to keep a low profile, he seldom discusses the movie that made him briefly famous, though he couldn't avoid the spotlight shown on the original cast members when Burton's splashy remake came out six years ago.

19. Ostrum was lured out of obscurity in 2009 by Dunkin' Donuts, which recruited him for a promotion that had him standing in a Boston subway station giving away CharlieCards (the fare cards Boston commuters use, which are named not for Charlie Bucket but for the hapless subway rider of the folk tune 'The MTA Song'). Ostrum gave out free fares and one Wonka-esque golden ticket, good for a year's worth of unlimited subway rides and free cups of Dunkin' Donuts coffee.

Peter Ostrum Gives Away CharlieCards for Dunkin' Donuts:

Wonka Exceptionals20. Quaker Oats sold the Wonka candy company to Nestlé in the 1980s. Nestlé relaunched the brand last year with a line of fancy, premium chocolate bars called "Wonka Exceptionals." Along with those bars and such familiar products as SweeTarts, Laffy Taffy and Pixy Stix, Wonka also sells Everlasting Gobstoppers, inspired by the movie.

Follow Gary Susman on Twitter: @garysusman.