The mysterious "fireflies" observed by 'John Glenn' on his first orbital flight were actually tiny flakes of frost illuminated by sunlight. As the spacecraft orbited into darkness behind the Earth, the sub-zero temperatures caused condensation on its skin to freeze. When warmed by the sun on the other side of the orbit, the temperature change caused some of this frost layer to break free and to be illuminated by the sun. This was confirmed by Astronaut Scott Carpenter on the next Mercury flight when he banged on the craft's side, causing more of the flakes to break free and become visible.
Parachute stuntman Joseph Leonard Svec was killed in an accident while filming the scene where Chuck Yeager loses control of an experimental aircraft and bails out. Svec's helmet filled with smoke and he lost consciousness. He never pulled his ripcord and died on impact. During the real-life bailout this scene represented, Yeager collided with his ejection seat, breaking open the face-shield of his helmet. Molten explosive materials struck Yeager in the face, burning him severely and likewise filling his helmet with smoke.
While several of the lead actors chose to meet their real-life counterparts, Scott Glenn elected not to meet with Alan Shepard. Scott said he wanted to get down Shepard's character and nuances by observation and by hearing others' points of view. After filming, the real Alan Shepard wrote the director and commented on Scott Glenn's "spot-on" performance - except for "not being nearly as good-looking as he was."
While filming the lung-capacity sequence - in which the seven original Mercury astronauts need to blow into individual tubes to keep toy balls suspended in a beaker and end up in a competition of physical stamina - the seven actors portraying the astronauts actually competed with each other for the same reason. Gordon Cooper was third, John Glenn was second and Scott Carpenter won (in the movie). In reality, Gordon Cooper - the astronaut portrayed by Quaid - was the only non-smoker among the seven original astronauts, and therefore possessed a far-greater lung capacity than any of the others.
When Ed Harris appeared in Apollo 13 (1995), it gave him the unique distinction of appearing with some of the same characters from The Right Stuff (1983) but played by different actors. Like Deke Slayton. Others are mentioned but never seen like Alan Shepard and the late Gus Grissom.
In the film, Alan Shepard says "Louise, I'm going to the moon, I swear to God. I'm on my way". Of the Mercury Seven, Shepard was the only one that did go there, on Apollo 14, becoming the fifth person to walk on the moon.
During the weekend of 4 April 1999, Gus Grissom's lost Liberty Bell 7 capsule was located and recovered on the ocean floor 90 miles northeast of the Great Abaco Island in the Bahamas. It underwent a restoration and went on a national tour before being placed in a permanent exhibit. The hatch, which many thought would have proved or disproved Grissom's contention that it blew open on its own, has not been recovered.
In the bar scene before Gus Grissom's flight, Deke Slayton is underwater swimming with some girls. Gordo says. "Go get 'em Deke!". In reality Deke couldn't swim and never told anyone. When the astronauts started underwater training at Scott Carpenter's suggestion, Deke sank to the bottom and had to be rescued. He subsequently practiced holding his breath underwater in his kitchen sink, according to his wife Marge.
This film contains the first realistic shots of a spacecraft reentry. For long shots, visual effects supervisor Gary Gutierrez used a small model of the Mercury capsule. This was coated with flammable material, ignited, and slid about 100 feet down a wire toward the camera, which was protected with a sheet of Lexan.
Trudy Cooper did not actually say that she wondered how they would've felt if every time their husband went in to make a deal, there was a one in four chance he wouldn't come out of that meeting." The screenplay writers chose Mrs. Cooper's character to voice statements made by Tom Wolfe, the author. The book describes a 23% chance of a normal pilot dying during the course of a 20-year career. The odds were higher at 53% for a test pilot, but this is still considerably less than was implied by the movie.
Ed Harris had to audition twice for the role of John Glenn. It was in fact Harris who insisted on the second audition because he felt his first reading of the part wasn't good enough. After the second reading, he got the part.
The scene where Alan Shepard is about to board the rocket to be the first American in space is archival footage. The scene immediately after he points up to the rocket after exiting the transport trailer shows a man in a suit and tie coming down the stairs of the trailer then following Shepard to the tower elevator. The man is the real Gus Grissom - one of the astronauts that perished in the Apollo 1 fire.
During the training montage, Gordon Cooper is shown sleeping in the simulated capsule, as loud noises and flickering lights are going off all around him. This is a nod to the fact that Gordon Cooper was the first American to sleep in orbit.
Original composer John Barry left the film because he found it impossible to understand what Philip Kaufman wanted from the score, citing a meeting where the director described his ideal score as "sounding like you're walking in the desert and you see a cactus, and you put your foot on it, but it just starts growing up through your foot."
For close-up shots of the reentry, no actual fire was used. The larger model capsule in these shots had liquid nitrogen pumped into it. This immediately evaporated, producing a fog of condensation, which escaped through a carefully placed ring of vents around the base of the capsule to form a flame-like pattern all around it. Then, to make the color right, the effect was simply filmed in orange light.
Some were concerned that when this film was released it would help propel John Glenn, then a popular political figure, into the presidency. "Newsweek" magazine had a cover story about it. In fact, Glenn's presidential aspirations went nowhere.
The closing narration states that Gordon Cooper was "the last American ever to go into space alone". While true when the film was made, Mike Melvill in June and September 2004 and Brian Binnie in October 2004 went into space alone in Scaled Composites' SpaceShipOne (Not a NASA spaceship or spaceflight). Binnie's flight was the day Gordon Cooper died.
The B-29 mother ship for the Chuck Yeager/X-1 scenes was played by the Commemorative Air Force's "FIFI," the only B-29 in flyable condition. She was painted up to match the actual mother ship used in the late 40's, complete with a dark under-belly so she would be more visible to ground personnel tracking her in the Mojave sky, and "stork delivering a baby" nose art. She appeared again, in the same paint job and nose art, in the Disney movie The Last Flight of Noah's Ark (1980). In the early 90's she went back to Boeing in Everett, WA, where she received a complete overhaul, new windows, doors and seals, and a fresh new paint job better matched to her role as a WWII bomber. FIFI is still flying today.
The film eschewed the use of visual effects done in the lab. The decision was made to use methods pioneered by Republic Pictures special effects team Howard & Theodore Lydecker, and used in such Republic theatrical serials as "Radar Men of the Moon" and "Commando Cody: Sky Marshal of the Universe.". The shots of the Bell X-1 were accomplished using a model 'flown' on a long wire rapidly passing by the camera utilizing a natural sky background enhanced by clouds created using special chemicals. The use of the model can be seen when the plane banks and turns as the ailerons never move.
The film plays down the rivalry between pilots, especially civilian (Scott Crossfield) and Air Force (Chuck Yeager). Yeager even writes in his autobiography that he thought Crossfield was arrogant, though a great pilot.
Tom Wolfe, was unhappy with the film because he felt it made too many changes to the book. William Goldman, the original screenwriter before he left the project also disliked it because he didn't like the way Philip Kaufman portrayed Chuck Yeager as the only hero in the film, while the rest of the astronauts only got lucky and didn't match up to him in any way.
Although Bill Conti's score won the Academy Award for "Best Music, Original Score" and suites based on the score were issued, no complete soundtrack album was released until 2009. That album was made from master tapes kept all that time by Conti, and unfortunately some suffered damage in the interim.
Chuck Yeager is credited in the role of Fred as "General" Chuck Yeager. In fact he is a two-star general, which carries the title "Major General". Chuck Yeager, in fact, retired as a brigadier, or one star general.
The tune that Gordon Cooper was whistling while trying to produce a semen sample, is the official anthem of the United States Air Force, simply titled: "The Air Force Song". He was attempting to drown out the man in the next stall, who was humming "The Marines' Hymn" (presumably, John Glenn, as Cooper guessed).
Allegedly composer Bill Conti wrote about three different scores for this film. The first consisting of his own original work. The second one being one that featured Holst's The Planets as inspiration. The final score purely copied the film's temp track which was primarily The Planet's peace under the condition that if 'Philip Kaufman' used that portion of the score he would've had to credit Gustav Holst, the real composer of the music knowing that he was plagiarizing it for Kaufman's benefit and did not want to take credit for something that was written by someone else. They had a compromise in the end, using the middle score that Conti wrote inspired by Holst, and the incorporation of "Wild Blue Yonder" during the Yeagher's Triumph sequence and Henry Mancini's White Dawn track stayed in the film. Conti would go on to win for Best Original score despite the fact that it was somewhat of an adaptation of The Planets.