According to a 1997 Comptique Magazine (March edition) interview with the game's director/designer/writer Tomoyoshi Miyazaki, he was asked why he chose Ark to be the only playable character. He responded:
"That was something that was decided at the very beginning, to only have Ark. Well, there’s also Yomi who you control inside Pandora’s Box. Because the player is alone in the story, we figured there should only be one character the player controls. That also makes it easier for you to empathize with the protagonist. One advantage was that since limiting the characters increases the memory available, we were able to do more complex and detailed movements and animation for Ark that we couldn’t do in the previous two titles. The controls are a step-up in that regard, I think."
According to a 1994 BEEP! Megadrive magazine interview with the game's producer/designer Koichi Kimura, he was asked if he was influenced by his love for Western animation for the game. He responded:
"Yeah. Actually western animation was one of the things that influenced me to get into the game industry in the first place. I really admire the sensibility of Looney Toons, where you never know what’s going to happen next. Watching them inspires me to hone my own skills. The difference between games and animation, though, is that in animation the artist directs how the scene moves and unfolds, whereas in games, that control is given over to the players. But I think that’s actually a strength for gaming and could lead to even more interesting scenes, which is something I want to explore more."
According to a 1994 BEEP! Megadrive magazine interview with the game's producer/designer Koichi Kimura, he was asked why many of the backgrounds use theater stage motifs (The spotlight, the curtains, rigging systems…). He responded:
"It’s just my personal taste. There’s a director named Terry Gilliam, who creates these fantastic, magical worlds that take place in the real world. He’ll do things like add an artificial sun to a normal, everyday scene. While I was designing Dynamite Headdy, I thought that kind of world would be cool, so we made a few mock-ups in that style. After seeing it in-game, I thought it looked great, so we doubled down and tried to make that a visual theme for the whole game. At this point in the development it might look really lame if we only went half-way with that aesthetic. There’s a bunch of other cool things we still plan to add, too."
According to a 1994 BEEP! Megadrive magazine interview with the game's producer/designer Koichi Kimura, he stated in regards to Headdy's character design and attacking with his head:
"I had been thinking I wanted the character to use some part of his body when he attacked, and throwing his head was something new, and would make an impact on players. I made him a puppet because puppets are easy to deform and manipulate, whereas a living creature that detached it’s head would be weird, I thought."
In a Reddit AMA with Shutaro Iida, he revealed that, for him and his team, the most insufferable thing about developing this game and for the Nintendo DS was strict demand from higher ups "to use the touch [screen technology] as much as possible" during their development.
Retro Studios, according to one of it's developers Bryan Walker, were at first extremely concerned about wanting to develop for Nintendo's upcoming Wii system due to the console's mediocre specs compared to the competition. However, being among the first westerners to see a prototype of the unique controller for the console, they were immediately won over by the gaming machine's groundbreaking motion-control gimmick.
“...And we were a little concerned to be blunt, and then, ta-da: they rolled out the Wii Remote. Kind of in unison, the whole team went, ‘Ohhhhh. Ahhhh. Okay.’ Everybody was watching at E3 where the Wii was rolled out and the stampede when they opened the door of people running right past the Sony PS3 display to get in line with the Nintendo display to play the Wii. We were like, ‘Ah okay. We understand now. We’ll be quiet.”
Retro Studios dev Bryan Walker recalled in an interview how unexpectedly understanding Shigeru Miyamoto was to him and his team's vision for the project in the planning stages and how considerate and mentorlike he was with their pitches and ideas. When the final moments of the collaboration were almost done, however, Walker recalled that Miyamoto said something in English to them that stuck with them forever: "Please take care of DK. He is my friend."
According to a 1994 BEEP! Megadrive magazine interview with the game's producer/designer Koichi Kimura, he was asked where the idea for Dynamite Headdy came from? He responded:
"The biggest reason for making Dynamite Headdy was that our team wanted to create something original. 2 I’ve been a part of many game developments, but almost all of them were either based on pre-existing characters, or plans that were handed to me from above, which I then adapted and revised. I thought Dynamite Headdy would be a more fun and fulfilling development. Having worked in game dev for 5 years now, I thought it was high time to make something of my own creation. I knew that if I wanted to make my own game, I needed to make something that looked convincing from a commercial sales perspective, and I put a lot of effort into the initial design and conception of Dynamite Headdy along those lines."
In a 1997 interview with the game's director Koji Igarashi & designer Toshiharu Furukawa, they were asked how they came up with ideas for the game's huge assortment of weapons and items. Igarashi stated that they used a variety of different references, books and other materials, and tried to include things that had never been used in a Castlevania game before.
Furukawa added that each of the staff members had a special attachment to a different kind of blade, so they ended up using a good variety of blades in the final game. However, this bias did result in the developers' favorite weapons being overpowered, adding that "Not realizing that no one liked shields was a bit of a blind spot…"
According to the game's director Tatsuya Nakae in a 2000 Arcadia magazine #3 developer interview, he was asked if he could comment about the three new original characters: SonSon, Amingo and Ruby Heart in the game. Nakae stated that until now, Norimaro had been the only original character in Marvel vs. Capcom series, so he wanted to add more new characters in the game from the start. When Nakae asked the game's lead character designer Katsuhiro Eguchi for some designs, Eguchi told Nakae that he wanted to revive someone from a classic game and sent him a design that reinterpreted SonSon as a girl; Nakae stated "it was interesting and had a lot of impact" and put the character in the game.
Nakae then stated that Amingo was designed to fulfill the missing role of a non-human Capcom character that was "capable of really crazy movements", and that Ruby Heart was designed to be the leading character of the three newcomers (in a marquee role similar to Ryu and Cyclops) and as a new challenge to create a "cool, female character", the kind of which had not commonly taken center stage in games released at the time.
In a 2001 interview with the game's director Jun Kobayashi featured at the game music column of allabout.co.jp, he was asked who his target audience for the game was. He responded:
"At first, I was thinking of a game for people who liked club music, something they could enjoy without actually going to the club."
"However, after mulling it over, we finally decided on targeting people who are new to video games with Rez. I mean people who maybe bought a Playstation 2 and watch DVDs on it, but hardly play any games. Or people who think “games today are too difficult, I can’t play them.”"
"By the way, I’ve been playing games since the Famicom era, so for most games today I don’t need to read the instruction manual, I can just start playing. That’s all good for people like me who grew up with and experienced the evolution of Famicom, Super Famicom, Sega Saturn, and Playstation… but Rez was aimed at those who don’t have that experience, the kind of people who have just bought a PS2 for the first time. The PS2 may be their first experience with a video game controller, and I wanted to create a game that even those new users could enjoy."
"With Famicom games you have a directional pad that moves a character, and when you press a button your character immediately jumps or attacks. I’m very familiar with those kinds of controls. Most games today are released for people like me, who are familiar with those kinds of controls, and developers then try to take that formula further and do more refined things with it."
"Consequently, people whose first video game console is the PS2 see these more complex games and have no idea what’s going on. The buttons are too complicated and the appeal of the game is lost on them. Of course with a player like me, I prefer those kinds of games, but with Rez I wanted to immerse new players in a different world: one where a brand new sensation has been added to the traditional formula of “aim and shoot the enemy”-type games. "
In a 1991 interview with the game's composer Yoko Shimomura published in vol. 62 of Gamest magazine, she was asked who did the voices for the game's characters. She stated that the team asked people at Capcom to perform them, and had about 30 different employees record their voices. She described it as a "kind of a chaotic jumble", and the team chose the best takes from the recordings, but at that point she had forgotten who voiced who. She also stated that the pronunciation for the English voices needed to be correct, so the team asked some non-Japanese people to voice them. In particular, E. Honda's “dosukoi!” line was originally voiced by a foreigner, although the team ended up not using it. They also tried having a man voice Chun-Li's “Spinning Bird Kick!” in a falsetto voice, but ultimately picked something different after more people auditioned.
In a 1991 interview with the game's composer Yoko Shimomura published in vol. 62 of Gamest magazine, she stated that she almost wrote all the songs in the game based on how she pictured each different country in her mind, and also tried to match the music with the stage backgrounds.
According to game's director Tatsuya Nakae in a 2000 Arcadia magazine #3 developer interview, he was asked how they were able to realize the support for the game's online matching service network (established in collaboration with Japanese telecom KDDI). He responded:
"In the beginning, Funamizu asked us if it’d be possible to add online battles as a major selling point, and after discussing it internally and determining that it might be feasible, we decided to approach KDDI with the idea. Thankfully, KDDI was on board and got to work on making it a reality; we didn’t have a ton of time for development, but thanks to the hard work of KDDI, we were able to make it happen." "At first, I was worried about lag during online matches, but when we ran in-house tests, the lag didn’t feel as bad as I feared it would and we were able to comfortably play online, so we rushed to finish the game. People who’ve never tried it tend to think “online play, I don’t know…” and shy away from it, but those people are the ones who are the most impressed when they finally try it for themselves, so I’d really urge you to go hands-on for yourselves."
According to the game's director Tatsuya Nakae in a 2000 Arcadia magazine #3 developer interview, he was asked why the team included two Wolverines in the game, one with bone claws and the other with adamantium claws. He commented that the team wanted to focus on the bone claw Wolverine, but the directive from Marvel was that both had to be included in the game. This made it difficult for the team to differentiate the two characters as they look almost identical, so they had to think of where and how to add pronounced, yet subtle differences.
According to game's director Tatsuya Nakae in a 2000 Arcadia magazine #3 developer interview, he was asked how Cable and Marrow were selected for this game? He responded:
"One of the staffers at our company is extremely well-versed in American comics, so we asked him to come up with a list of candidates. Using the selection criteria of “attacks that can be easily understood at a glance” and “doesn’t significantly overlap with any of the characters introduced with the previous games”, as well as “cool factor”, we narrowed the selection down to those two."
"With regards to Cable in particular, we also factored in his slightly convoluted backstory as Cyclops’ son from the future as something that players would find fun."
According to the game's producer Yoshihiro Sudo in a 2000 Arcadia magazine #3 developer interview, he acknowledged that the line charge for the arcade release of the game in Japan charging 13 yen per minute, meaning 50-60 yen per game, was a controversially high rate that the developers did not want to increase and that fans complained about for being too high, but that it was the lowest possible price they could charge the game at for the time being. He then expressed hope that the cost would lower as more people played the game.
According to game's artist Ben Fiquet on his Twitter account, the elevator platform from "Stage 11: Airplane" was inspired by the manga series Akira. The name of the stage's soundtrack is even "A Ki Ra".
During the level "A Hole in Space", if you collect all 18 Bumpa Berries while riding the grind rail, you will be rewarded with a visual effect of a group of low-poly Crash Bandicoot/Coco models screaming "Woah!"/"Yeah!" respectively, while also earning the achievement "WHOA YEAH!". This is a reference to a CG animation created by Chris Patstone and based on an audio clip voice acted by animator Chris O'Neill which became a meme in 2017. The in-game reference uses individual frames of the same model of Crash featured in the original video, but O'Neill's voice is dubbed over. The Coco model is used from a pre-existing variant on the meme created by animator Zellphie.
During the level "A Hole in Space", if you collect all 18 Bumpa Berries while riding the grind rail, you will be rewarded with a visual effect of a group of low-poly Crash Bandicoot/Coco models screaming "Woah!"/"Yeah!" respectively, while also earning the achievement "WHOA YEAH!". This is a reference to a CG animation created by Chris Patstone and based on an audio clip voice acted by animator Chris O'Neill which became a meme in 2017. The in-game reference uses individual frames of the same model of Crash featured in the original video, but O'Neill's voice is dubbed over. The Coco model is used from a pre-existing variant on the meme created by animator Zellphie.