forrest gump factsYou've probably seen "Forrest Gump," which makes its IMAX debut September 5, so many times in the 20 years since its release (on July 6, 1994) that you can recite the dialogue by heart, starting with the line about life being like a box of chocolates.

You probably know that the film won six Oscars, including Best Picture, Best Director (for Robert Zemeckis), Best Actor (for Tom Hanks), and Best Adapted Screenplay (for Eric Roth). You may even know about the digital trickery that was used to insert Hanks's low-IQ Everyman into historical footage of real-life events from the Baby Boom years, or to erase Gary Sinise's legs for his role as double-amputee Lt. Dan.

Still, there's a lot you may not know, including what Forrest really said (in Winston Groom's novel that inspired the film) about life being like a box of chocolates, or what Hanks's Gump actually said at that protest rally, or which famous actors almost played Forrest's pal Bubba before Mykelti Williamson landed the role, or the unlikely location where the Vietnam sequences were filmed, or which historical figure played himself and was not digitally "gumped" into the film, or the bizarre accounting that appeared to cheat the author while paying the star eight figures.

Here, then, are the secrets of the Gump.

1. The character of Forrest Gump in the movie is a lot more passive and naïve than in Winston Groom's 1986 novel, where he's more cynical and abrasive. For instance, the actual line about chocolates, which opens the novel, is this:

Let me say this: bei'n a idiot is no box of chocolates. People laugh, lose patience, treat you shabby. Now they says folks s'posed to be kind to the afflicted, but let me tell you - it ain't always that way. Even so, I got no complaints, cause I reckon I done live a pretty interestin' life, so to speak.

2. Groom's Gump is also a more heavyset man than Hanks; the author later said he would have cast John Goodman in the role. 3. There are other major differences. For instance, a subplot in which Groom's Gump becomes an astronaut was left out of the film. On the other hand, most of Forrest's fondness for running is an invention of screenwriter Eric Roth.

4. Hanks claimed to have ad libbed the line, "My name is Forrest Gump. People call me 'Forrest Gump'"

5. Dave Chappelle, David Alan Grier, and Ice Cube all reportedly turned down the role of Bubba. Chappelle had thought the film would tank and later regretted his decision. He'd eventually play Hanks's pal in "You've Got Mail."

6. Mykelti Williamson wore a prosthetic to extend his lower lip throughout his performance as Bubba.

7. After a decade and a half of TV work, Williamson complained that, for a while after the release of "Gump," no one would hire him because casting directors thought Zemeckis "had discovered some weird-looking guy and put him in front of the camera." Fortunately, a guest appearance on "The Late Show With David Letterman" made clear that the real Williamson was nothing like Bubba.

8. Kurt Russell, who was nominated for an Emmy for his role as Elvis Presley in the 1979 TV movie "Elvis," claimed to have provided the voice for the barely-seen Elvis in "Forrest Gump" Russell had starred in Zemeckis's 1980 comedy "Used Cars."

9. The actor who plays legendary Alabama football coach Paul "Bear" Bryant is Sonny Shroyer, the actor best known for playing deputy Enos on TV's "The Dukes of Hazzard."

10. Yes, that's Haley Joel Osment, future "Sixth Sense" star, making his movie debut as Forrest Jr.

11. Zemeckis's son Alexander and Hanks's daughter Elizabeth are among the kids on the school bus who greet young Forrest with scorn on his first day of school.

12. Hanks learned his heavy Southern accent from Michael Humphreys, the Mississippi native who played Forrest as a boy.

13. Sally Field is only 10 years older than Tom Hanks. Six years before he played her son in "Gump," he wooed her in "Punchline."

14. Robin Wright ("Jenny") had a cold during the strip club scene but managed to sing while naked for the roughly 24 hours that it took to shoot the sequence.

15. Most of the film was shot in and around Beaufort, S.C., including the scenes set in Vietnam. The Gump House was a set built on land near the Combahee River.

16. There is no bus stop bench at the plaza in Savannah, Georgia, where Forrest sits while telling his life story. The bench was brought in by the filmmakers. Today, it's in a history museum in Savannah.

17. Ken Ralston and his special effects team at Industrial Light & Magic earned much praise -- and an Oscar -- for the effect that came to be called "gumping" -- using CGI to insert Hanks into existing historical footage. (Zemeckis's team also used digital effects to change the mouth movements of historical figures in the old footage, then added his own voice actors, so they would appear to be conversing with Hanks.) In one case, for instance, the effects artists used footage of President Lyndon Johnson giving an award to Sammy Davis Jr. and superimposed Hanks's likeness over Davis's to make it look like the president was giving Gump a medal.

18. The scene in which hundreds of thousands of people appear on the Washington D.C. Mall for an anti-Vietnam War protest rally was accomplished with just 1,500 extras, recruited from a local Renaissance Fair so that they would already have what appeared to be hippie clothes and hair. They were filmed as a group in various locations on the Mall, and the footage was then assembled into panoramic crowd shots via computer.

19. Almost all of Forrest's speech at the Vietnam War protest rally is inaudible because his microphone is shut off, but Hanks has said the words he uttered were: "Sometimes when people go to Vietnam, they go home to their mommas without any legs. Sometimes they don't go home at all. That's a bad thing. That's all I have to say about that."

20. Dick Cavett is the only famous historical person playing himself, rather than appearing in archival footage. In the sequence where the talk show host interviews Forrest about playing ping pong in China, you're seeing the 1993 Cavett, made up to look like his younger self, along with old footage of John Lennon from a 1970s appearance on Cavett's show.

21. Hanks won back-to-back Best Actor Oscars for "Philadelphia" and "Gump," becoming the first man to win two lead acting Oscars in a row since Spencer Tracy did it in the 1930s.

22. The movie cost a reported $65 million to make. It earned $330 million at the North American box office.

23. Hanks took no salary up front but earned a percentage of the film's gross profits (meaning: he and other gross profit participants got paid out of ticket sales before anyone else did) that was ultimately worth $40 million.

24. Groom earned $350,000 for the movie rights to the novel, plus 3 percent of the film's net profits (meaning, he was to be paid only after gross profit participants like Hanks and all other costs associated with making and marketing the film were paid). A year after the film's release, he'd received no net profits because Paramount argued that the movie hadn't earned any and was still $62 million in the red, despite its $660 million in worldwide sales. Groom complained publicly and ultimately received from the studio a seven-figure sum that included a payment for the film rights to his 1995 sequel, "Gump & Co."

25. In Groom's follow-up novel, Forrest complains about the inaccuracy of the movie and, in one sequence, meets Tom Hanks. As recently as 2010, Paramount was still trying to develop the book into a movie sequel, but Hanks has refused to reprise his Oscar-winning role.

In honor of its 20th anniversary, "Forrest Gump" is getting a special IMAX re-release, starting Friday September 5.

Photo courtesy Paramount / Everett Collection

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