Hugh Jackman said that for his shirtless scenes in the film, he wanted to look "as ripped and cut as possible". So he adopted a dehydration diet (used in bodybuilding) where he did not consume any liquid for 36 hours before filming his shirtless shots. He said it made him feel "headachy" and faint, but he was pleased with the results, as dehydrating tightens everything up and gave him the exaggerated muscle definition and vascularity that he wanted to show in his shirtless scenes.
To prepare for the role, Hugh Jackman contacted Dwayne Johnson for advice on bulking up for the movie. Johnson suggested Jackman could gain a pound a week over six months (24 weeks) by eating 6,000 calories a day of "an awful lot of chicken, steak and brown rice."
The film was scheduled to be released in Japan in mid-September, more than a month after its worldwide release. This was to avoid insensitive screenings during the early August anniversaries of the atomic attacks on Hiroshima and Nagasaki (the film itself opens with the Nagasaki bombing).
Wolverine's claws were redesigned for this film. The older version was a straighter design, but the new claws have more cuts and angles to them, allowing them to reflect light easier. Also, the claws come out of the hand lower, towards the palm, which makes more sense from a scientific perspective. The older claws came out a bit beyond the knuckles. The new claws appear like they come out from in between the fingers, which means they could retract straight back into the forearm.
Hugh Jackman said that with this film, he finally achieved the physique that he always envisioned in his mind that Wolverine should have. He said that for some reason, on each of his five prior takes at the character, he felt that he never had enough time to get in shape; for this film he finally had enough time, and got his body exactly the way he wanted it to look. Co-star Will Yun Lee also said that it was Jackman's best physique for the role of Wolverine.
Hugh Jackman is a self-confessed fan of the Chris Claremont-Frank Miller "Wolverine" comic (1982), especially the Japanese saga: "There are so many areas of that Japanese story. I love the idea of this kind of anarchic character, the outsider, being in this world full of honor and tradition and customs; someone who's really anti-all of that, and trying to negotiate his own way. The idea of the samurai too, and the tradition there - it's really great. In the comic book he gets his ass kicked by a couple of samurai - not even mutants."
Guillermo del Toro expressed interest in directing, being a fan of the Japanese saga in the "Wolverine" comics. He met with James Gianopulos and Hugh Jackman about directing the film, but ultimately decided he did not wish to spend 2-3 years of his life working on the film.
According to Hugh Jackman, Wolverine being surrounded by death while being unable to die, due to his healing factor, is a major theme in the film: "He realizes everyone he loves dies, and his whole life is full of pain. So it's better that he just escapes. He can't die really. He just wants to get away from everything."
Famke Janssen filmed her Jean Gray cameo in three days. Hugh Jackman said, "There's no doubt that the most important relationship in his life is - we've seen through the movies - is his relationship with Jean Grey. Yes, we saw her die at the end of X-Men: The Last Stand (2006), but in this movie, she has a presence which I think is vital to the movie, particularly for him confronting the most difficult thing within himself."
Hugh Jackman confirmed on having discussions with James Mangold about test screening a PG-13 rated cut, and an R rated cut, but did not comment on filming sequences for them. Although the film was confirmed to be rated PG-13 via a tweet from James Mangold, saying "it's PG-13, but don't worry, it ain't Bambi (1942)." An unrated and extended cut is confirmed exclusively for the 3-D Blu-ray release.
According to James Mangold, the film had started out as a prequel to X-Men (2000), but later he decided to make it a sequel to X-Men: The Last Stand (2006): "I wanted to tell the story without the burden of handing it off to a film that already exists and having to conform to it. The ideas of immortality reign very heavily in this story, and the burden of immortality weighs heavily on Logan. For me that's such an interesting part of Logan's character that it is nearly impossible to explore in a prequel."
The movie is written as a stand-alone story, with very little connection to past or future X-Men films. 20th Century Fox embraced the idea of this film being different, and were even the ones to come up with the title The Wolverine. The story does feature other mutants, and that includes other mutants from the X-Men universe. James Mangold says there was no pressure from the studio to connect this story with the other X-Men films, previous or future. There is no set-up in this story for future films, as far as he knows. Mangold says "Our goal is to make something that doesn't rely on franchise."
For the bullet train fight, the actors and stunt performers filmed on wires above a set piece surrounded by greenscreen. The moving background came from filming on an elevated freeway in Tokyo. The visual effects artists got the background from filming with a rig and eight Red Epic cameras angled at 45 degrees. Filming at sixty kilometers per hour, the footage was then sped up to three hundred kilometers per hour.
Darren Aronofsky was originally set to direct and worked on the project for six months before departing, citing the long overseas shoot would prevent him from seeing his family (he had just separated from Rachel Weisz, the mother of his child). During his time attached to the film, he rewrote the screenplay by Christopher McQuarrie and it is speculated that the real reason for his departure was the studio's unwillingness to approve his draft - which aimed for a hard 'R' rating due to heavy sexual content and brutal violence.
According to James Mangold, this film is a sequel to X-Men: The Last Stand (2006) ("Jean Grey is gone and most of the X-Men are disbanded, so there's a tremendous sense of isolation for Wolverine") but with extended flashbacks.
Yukio's hair is dyed bright punk red. Rila Fukushima read the comics in preparation for the role, and was shocked that they wanted her to have dyed red hair, as her comic book version had long black hair, which is what she has naturally.
Almost all the promotional materials for the film and the posters featured a shirtless Hugh Jackman; in contrast, he appears shirtless only in a handful of scenes in the actual film. This was done in order to emphasize the superior shape he got into for the film.
Wolverine's response after being asked 'How did you know there was a pool down there' ("I didn't") is a reference to the Bond film Diamonds Are Forever (1971), where the gangster quips "I didn't know there was a pool down there!" after throwing Plenty O'Toole out of a window.
Doug Walker a.k.a. The Nostalgia Critic, had a cameo in the extra scene after the end credits and can be spotted standing in the background behind Wolverine. When Wolverine turns around and sees that everybody at the airport has frozen in time.
David Leitch says the stunt work in this film is more gritty, and grounded in reality, in contrast to the previous films. They have decided to tackle more of the stunts using practical means, and not rely as much on post-production CGI.
When they shot in Japan, the crew wasn't able to completely lock off the streets, so they shot guerrilla style with a Japanese crew trying to block normal people from getting in shots. This movie features a chase sequence that takes place in the city streets of Japan, with Silver Samurai in black leather, with a bow and arrow, running around on roof tops trying to shoot Logan down. A real-world feel in a contemporary city. The cast of the film is almost entirely Japanese.
Rila Fukushima and Tao Okamato would go on to star in DC comics properties with Fukushima playing Tatsu Yamashiro/Katana in the CW series Arrow (2012), while Okamato plays Mercy Graves in Batman v Superman: Dawn of Justice (2016).
The movie was being shot on all six sound stages at Fox Studios Australia, a international production facility, which was also used for The Matrix (1999), Moulin Rouge! (2001), Mission: Impossible II (2000), Star Wars: Episode II - Attack of the Clones (2002), Star Wars: Episode III - Revenge of the Sith (2005), and Superman Returns (2006). In 1999, Fox opened the 261 million dollar theme park on the grounds (think an experience like Universal Studios Hollywood). Fox Studios Backlot theme park closed in late 2001 due to poor ticket sales.
Logan refuses to use the name "Wolverine" until later on, when he finally declares it to his enemy Shingen before killing him. This is an homage to the storyline "Old Man Logan", where he renounced the title until the very end, when his enemies had slain his family.
The Silver Samurai (Ichiro Yashida) in this film is a combination of Kenuchio Harada (a skilled mutant samurai with a tachyon blade) and his son Shin Harada (who possesses a technologically-advanced suit of armor); Shin himself is a separate character in the film. The Silver Samurai is also based on Ogun, a supervillain and enemy of Wolverine who had given him a sword and tried to steal Wolverine's immortality.