When Forrest gets up to talk at the Vietnam rally in Washington, the microphone plug is pulled and you cannot hear him. According to Tom Hanks he said, "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."
When the studio imposed budget cuts, both director Robert Zemeckis and star Tom Hanks waived a large part of their fee in exchange for percentage points, which ultimately netted Hanks in the region of $70 million.
When Forrest first learns to play ping-pong in the infirmary, he is told the trick is to "keep his eye on the ball at all times" by another soldier. After that moment, whenever he is shown playing ping-pong, he never blinks.
With every transition of Forrest's age, one thing remains the same. In the first scene of each transition, he wears a blue plaid shirt.
Tom Hanks signed onto this film after an hour and a half of reading the script, but agreed to take the role only on the condition that the film was historically accurate. He initially wanted to ease Forrest's pronounced Southern accent, but was eventually persuaded by Robert Zemeckis to portray the heavy accent stressed in the novel, and he patterned his accent after Michael Conner Humphreys (young Forrest), who actually spoke that way. The crew and especially studio head Sherry Lansing initially had serious doubts about Hanks' goofy accent, but Zemeckis stuck to his guns.
Kurt Russell: Uncredited, as the voice of Elvis Presley. Russell previously worked with Robert Zemeckis on La fantastica sfida (1980). He also played Presley in Elvis, il re del rock (1979), and made his film debut at age 12 in Bionde rosse brune... (1963), in a scene where he kicked Presley in the shin. The young Russell originally didn't want to kick Presley, because he was a fan, so Presley paid him $5 to do it.
Alexander Zemeckis: The first boy in the school bus who refuses to let Forrest sit next to him is Robert Zemeckis' son.