"Houston, we have a problem."

One of the all-time great lines from any movie, let alone Tom Hanks' estimable body of work, and one that swiftly transcended the film it came from to become a catch-all phrase applied to any issue, however major or minor.

But the problem that drives the action in Apollo 13 was a real life-or-death turn of events for the three astronauts aboard the 1970 lunar mission of the same name, and the inherent suspense in how their myriad seemingly impossible problems got solved is what made the Ron Howard-directed movie so good when it came out in June 1995—and still so watchable (and somehow still suspenseful) more than years later.

Even if you already knew what happened before you ever saw it. 

The Apollo 13 crew—commander and pilot Jim Lovell Jr., command module pilot John Swigert Jr., and lunar module pilot Fred Haise Jr.—were approximately 100,000 miles away from Earth when wiring in the oxygen-stirring fan short-circuited and ignited the Teflon insulation, causing an explosion—and resulting in quadruple failure as they could literally see their oxygen floating into the ether. 

Not that anyone in space or on the ground knew what had caused the explosion at the time. Rather, what they knew was that the crew's chances of survival all of a sudden seemed slim.

But a lot of sweat and lost lunches goes into making a realistic-looking film about astronauts in mortal peril, so from our own personal mission control we've compiled the most compelling facts about the making of Apollo 13.

1. Jim Lovell was "probably the most well-liked of all the astronauts," Tom Hanks shared in a behind-the-scenes interview in 1995. "He was very easy-going—notoriously easy-going, as a matter of fact."

Plus, longtime space enthusiast Hanks had always wanted to play an astronaut (and he went on to host and executive-produce the 1998 miniseries From the Earth to the Moon).

So, spot-on casting choice... check.

2. In addition to this movie being based on true, more harrowing-than-fiction events, the screenplay by William Broyles Jr. and Al Reinert was adapted from the 1994 book Lost Moon, by Lovell and journalist Jeffrey Kluger.

3. Ron Howard was determined not to include any footage from the actual mission, so two individual Lunar Module replicas and two Command Modules were constructed for the movie. He also had iconic news anchor Walter Cronkite re-record some of his lines from his CBS broadcasts reporting on the state of the mission.

4. Spacecraft interiors were constructed by the Kansas Cosmosphere and Space Center's Space Works, which had also restored the actual Apollo 13 command module.

5. Hanks, Kevin Bacon and Bill Paxton trained at the U.S. Space Camp in Huntsville, Ala.

6. In the film, the Apollo 13 crew plays "Spirit in the Sky" after their successful launch, but in reality they played the theme from Stanley Kubrick's 2001: A Space Odyssey—which had just come out in 1968 and also inspired the name of their command module, Odyssey (also so named for its Homeric significance).

7. To get that zero-gravity feeling, they spent 13 days filming in a weightless environment, made possible aboard NASA's specially modified KC-135 Stratotanker, a Boeing-designed military aerial refueling aircraft aptly nicknamed the "Vomit Comet," which could achieve about 23 seconds of zero-G at a time.

"All the blood goes into your head, and it feels like when you're on a Rock-O-Plane at the amusement park, it just feels like you've got spun upside down," Hanks described the experience. "...Then you realize, oh, I guess this is weightlessness."

8. The Saturn V SA-508 rocket carrying the Apollo 13 mission really did blast off at 14:13 (military time for 2:13 p.m., ET) from the Kennedy Space Center in Florida—and in Houston (CT), that was 13:13.

9. Lovell didn't say "Houston, we have a problem," exactly.

According to recordings from that day, Jack Swigert (played by Bacon) was first to tell mission control, "OK, Houston, we've had a problem here," but part of the transmission was garbled and he was asked to repeat himself. 

Lovell then reiterated, "Houston, we've had a problem."

10. Flight Director Gene Kranz didn't really tell his men that "failure is not an option," either—but Kranz did borrow the also-very-iconic directive uttered in the film by Ed Harris for his 2000 autobiography, Failure Is Not an Option: Mission Control From Mercury to Apollo 13 and Beyond.

11. The real Mission Operations Control Room, located at what is now the Lyndon B. Johnson Space Center (then the Manned Spacecraft Center) in Houston. 

12. Fred Haise, played by Paxton, really did throw up a little (and just once) in space, but from lingering effects of a virus, not motion sickness.

They used Beef-a-Roni for space vomit and, after losing some sort of bet with Hanks, Paxton ate whatever was left in the can.

None of the actors actually did throw up aboard the "Vomit Comet," according to them at least, but some crew members did.

13. Lovell was Neil Armstrong's backup for Apollo 11, and then he was put on the schedule for Apollo 14, but he and his crew were bumped up in line. 

"I went home and I told my wife, 'We're gonna go on 13, not 14,' and she said, '13?'" Lovell recalled in an interview with Astronomy magazine. "I said, 'Well, it comes after 12.' Then they put that in the movie."

14. Kathleen Quinlan (who made her movie debut in 1973's American Graffiti co-starring Howard) was nominated for a Best Supporting Actress Oscar for her turn as Marilyn Lovell, Jim's high school sweetheart and wife since 1952. And just as the actors immersed themselves in that NASA world to prepare, Quinlan did her research into what it was really like being an astronaut's wife. 

"I met Marilyn, and she was so gracious and helpful," Quinlan recalled to Smashing Interviews in 2014. "Jim and Marilyn flew me to Houston. Jim actually flew the plane, and Marilyn sat in the back serving coffee. It was really cute."

"I met a lot of the astronauts' wives, and I realized when I met them and talked with them what a strong, important influence they were on their husbands and where they were in their minds before they took off," she continued. "They had to be really ready, and it had a lot to do with who was there supporting them. Marilyn was very helpful."

15. Brad Pitt was reportedly offered the role of Lovell but turned it down to star in Se7en. It worked out well for everyone involved, and Pitt eventually went to space in 2019's Ad Astra. At 32, he was actually on the young side to play Lovell, who was 42 when the events of the film occurred.

16. Hanks was only 38 and therefore also a few years shy of Lovell's actual age, but coming off of two straight Best Actor Oscar wins, for Philadelphia and Forrest Gump, there was no bigger movie star in the world to cast as your leading man. His personal nomination streak came to an end in 1996, though Apollo 13 was nominated for nine Oscars, including Best Picture, and won two, for Best Film Editing and Best Sound.

17. In additional film commentary, Marilyn Lovell basically said that Hanks nailed her husband's mannerisms so, really, there's no bigger honor. One more honor: in 1996, Hanks had an asteroid named after him, the "12818 Tomhanks."

18. Clint Howard is "that guy!" in so many movies, including many made by his big brother Ron Howard—and his memorable turn as Johnson during the phallic euphemism sequences in the Austin Powers trilogy is pretty much a parody of his character in Apollo 13, NASA flight controller Sy Liebergot, who was in charge of the electrical and environmental systems aboard the command module.

19. That's their father Rance Howard as the minister who's at the Lovell family's side as they hope, wait and pray for for Apollo 13's safe return.

20. That's Lovell himself playing the captain of the USS Iwo Jima, the recovery ship dispatched to greet the Apollo 13 crew upon their return to Earth. In fact, it's Lovell wearing his own captain's uniform. Howard wanted to cinematically promote him to admiral, but Lovell insisted on portraying the actual rank he had achieved when he retired from the Navy.

Lovell recalled telling the director, "'I'll dig out the uniform of a captain—my own uniform. I'll dust it off. I'll put on the ribbons that the actual [skipper] had so it will be authentic, and I'll go from there.' It was my uniform. I took it out and put in on to make sure it didn't have any spots on it."

21. At least one critic hadn't done their homework: Howard remembered seeing a comment card after a screening that dismissed the film's "typical Hollywood" ending—because in reality those astronauts would've never survived, wrote the film-but-not-history buff.

Above, the actual Lunar Module Aquarius being recovered by the USS Iwo Jima upon splashdown in the South Pacific on April 17, 1970.

22. The famous "square peg in a round hole" scene when the guys on the ground try to build a filter using only whatever the astronauts have on board the Saturn V supposedly inspired the British competition series Scrapheap Challenge—called Junkyard Wars when the U.S. adopted the concept.

23. A 20-by-8-foot mural called "The Steeds of Apollo" that was on display at the St. Regis Hotel in New York inspired the patch, designed by Lumen Martin Winter, that the Apollo 13 crew wore on their uniforms after the astronauts saw the mural during a visit to the hotel.

Decades later, Lovell mentioned to Hanks that he had seen that the mural was in the catalog for an upcoming art auction in Santa Monica, Calif. Naturally, Hanks' wife Rita Wilson and her mother went to the auction, bought "The Steeds of Apollo," and the family gifted the painting to Lovell, who had it installed at his family's Chicago-area restaurant, Lovells of Lake Forest. Before the restaurant closed in 2015, he donated it to the Capt. James A. Lovell Federal Health Care Center in Chicago.

24. Ken Mattingly, who was replaced by Swigert on the crew after he was exposed to rubella and didn't have immunity, was in the Mission Control room in Houston when Apollo 13 launched. He later orbited the moon as a member of Apollo 16 in 1972.

"Ken is 79 years old now and still never had the measles," Haise told Gulf Live in 2015 during an appearance at Stennis Space Center in Mississippi, a day after the 45th anniversary of the splashdown in the South Pacific Ocean.

Haise called it lucky for the Apollo 13 crew that Mattingly, who was intimately familiar with the spacecraft, was there on the ground when the accident happened. "Ken was a key person in bringing us home," he said. "The movie is somewhat limited in what they can show in two hours."

25. When the film came out in 1995, reporter Barbra Zuanich-Friedman, who personally knew Capt. Jack Swigert (at left), objected to his portrayal in the film as a brash ladies man who along with Haise played second fiddle to the heroic Lovell—and whose readiness for the mission is questioned before and after the accident aboard the command module Odyssey.

"I was disappointed in the one-dimensional portrayal of rookie astronaut Swigert, whom I met in 1968," Zuanich-Friedman wrote for the Los Angeles Times. "[Kevin Bacon] was forced to play Swigert a bit lopsided—first giving us the impression that in his off-hours he was a cocky, skirt-chasing bachelor and later portraying him as an intimidated, insecure and perhaps resented member whose every move was scrutinized for error."

Swigert "was always the epitome of good manners," she also wrote. "He was shy, good-humored, optimistic and intense. I learned about his love for flying that captured him at age 14 and never let go...For the record, he was uniquely qualified to step into the difficult job of maneuvering Apollo 13's command ship Odyssey."

26. This marked the second of, to date, five films that Ron Howard has directed Hanks in, the longtime friends beginning their fruitful association with the 1984 mermaid-out-of-water rom-com Splash.

"It's a movie that hopefully makes you understand what it was like to be there, what it was like to be in the capsule," Howard said when the film came out. "What it was like to be at home waiting for people that you loved to get back. What it was like to be in mission control with no sleep, and trying to make crucial calculations to send up to these three men who were relying on that information."

Thanks to this film, you can guess.

This story was first published on Tuesday, June 30, 2020 at 7 a.m. PT.