The teenage versions of the Washio brothers (seen in flashbacks) are played by Shinta Takaiwa (Fu) and Taiga Watanabe (Rai), the sons of Kamen Rider suit actors Seiji Takaiwa and Jun Watanabe, who in this series play Build and Night Rogue respectively.
Pepsiman for Build himself due of his main colouration being red and blue, and his trinkets being bottles. Doesn't help that his first power up will be based off a can and adds some white to the colors.
Hokuto's Prime Minister Yoshiko Tajimi has been nicknamed "Crazy Hokuto Lady" by some fans due to how little her actual name is brought up in-series. Similarly, there's "Slimy Seito Bugger" for Masakuni Mido, due to his generally low-key demeanor despite being hit with the same Hate Plague as Gentoku and Yoshiko (particularly after the payoff halfway into the series).
Vernage is often nicknamed "Useless Queen of Mars" due to her VA's more famous role as a certain Useless Goddess. It's rather ironic, given Vernage is the only reason the heroes have ever had any chance at all to stop the Big Bad.
Prior to joining Team Build, Kazumi was dubbed "Greasy Boy" or "Grease Man" in reference to his Kamen Rider name. Kazumi is also tricky because it sounds similar to Kasumi, who died in the second episode. Now that his name comes up more, its died down.
Some fans refer to Shinobu Katsuragi's Rider form as Another Build, partly because that's the title of the episode featuring him and partly in reference to Another Agito. Ironically, Kamen Rider Zi-O introduced an actual Another Build a mere week after Build ended.
A lot of fans caught on to the hints that Sento was Katsuragi long before episode 15 confirmed it.
Other fans had a hunch that Gentoku would become Kamen Rider Rogue as a potential Mid-Season Upgrade.
On a side note Evolt was later revealed to be the true villain pulling everyone's strings.
Although it wasnt unanimous, Nariaki becoming Mad Rogue was something a lot of people guessed.
Meme Acknowledgement: The final episode nods to a couple of the show's more popular memes: In the new world, Sato Taro is a famous rockstar while Sento Kiryu is literally unknown. Soichi and Misora (who are fans of Taro's) quote his memetic "We're having yakiniku tonight!" Meanwhile, Utsumi (who's working in a factory) tries to snap a metal bar over his knee like he did Nanba's cane...it doesn't go so well for him this time around.
Atsuhiro Inukai, Sentos actor, mentioned at a press conference that he watched Kamen Rider Kabuto when he was in middle school.
Eiji Akaso, who plays Ryūga Banjō, has said that his favorite Rider is Kuuga and his grandfather once gave him a toy Arcle for his birthday.
Yukari Taki, the actress for Sawa Takigawa, has expressed that her favorite Shōwa and Heisei Riders respectively are Kamen Rider V3 and Kamen Rider Accel, the latter of whom she actually costarred with in his own V-Cinema.
Yasuyuki Maekawa, the actor for Sōichi Isurugi, stated in a press conference that Skyrider and Stronger were his favorite Rider series growing up.
Shōgo Mutō, the shows head writer, said in an interview that he became a fan of the Heisei Riders while watching the shows with his son, and that his overall goal with Build is to create a series that kids and adults alike can enjoy.
Prop Recycling: As revealed by merchandise scans, Build's Legend Rider forms are literally just the original Rider costume with the Build Driver in place of their own belt, just like Kamen Rider Decade (ironically enough, he even has a Decade Form). This is presumably a cost-cutting measure, considering several recent Rider shows had specially-made Legend Rider suits that were only used once and then never againnote Though Ex-Aid made the most of it by recycling those suits into ones actually used in the show, like Big Bad Cronus being recycled from Genm Wizard Gamer.
Done in the show with the Smash monsters as its first used as regular Smash and then the (supposedly) upgraded Smash Hazard.
The CGI models for the "energy cobras" that Blood Stalk can summon are actually Venosnaker, Kamen Rider Ouja's Bond Creature; the only difference is that they're rendered in light blue and lack the gold blade-fins along the body.
As with many Rider shows, several later costumes are made by recycling existing costumes, mix-and-matching and repainting parts to make them look more unique.
Grease Blizzard is a combination of Grease's helmet, chest armor and right bracer with the base suit and Destruction One claw arm from Build PhoenixRobo Form, all repainted blue.
Prime Rogue from the Hyper Battle DVD is Rogue's armor (helmet, chestplate, bracers and boots) worn over a spare Build bodysuit, all given tons of gold filigree.
In NEW WORLD: Kamen Rider Cross-Z has Cross-Z Evol is a combination of Evol Black Hole form's horns mixed Cross-Z's helmet and Evol Black Hole's waist cape. All Repainted in Neon and dark cyan
Kamen Rider Killbas is a repainted combination of made parts of Blood Stalk and Night Rogue/Mad Rogue's helmet, Blood Stalk's shoulders and gauntlets and Hazard Form's feet and shins.
The Scorpion and Gold Fullbottles were supposed to be among Hokuto's tally of Fullbottles, but they were replaced by Rose and Helicopter.
Similarly, F1 and Kyoryu (Dinosaur) Fullbottles were most likely replaced with Santa and Cake Fullbottles, with fans guessing that there's an issue with the use of the "F1" name. Christmas-themed gimmick items usually are not part of the story (such as with the Santa Claus Eyecon from Kamen Rider Ghost toyline series, or the Holy Christmas Shift Car from Kamen Rider Drive toyline series), but the Santa and Cake Fullbottles are part of the story, likely due to Toei using them as replacement.
Notably, due to the existence of regular Bat and Engine Fullbottles, Toei could have replaced F1 and Kyoryu with regular Crocodile and Remote Control Fullbottles, allowing them to keep Santa and Cake Fullbottles out of the series. It is not known why Toei didn't choose to do so.
It's possible that at one point, a crossover between Build and Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger was planned, as indicated by a Super Sentai Full Bottle toy (which explicitly shows the 2 Red Rangers from the series, as opposed to a generic Sentai teamnote granted, there's also a Kamen Rider fullbottle which shows Build, Cross-Z, Grease, and Rogue), and a sound effect exists specifically for Build on the VS Changer in addition to the general "Kamen Rider" sound effect, but was scrapped; possibly due to the decision to stop making spring crossover movies (which all previous crossovers had promoted). Its unknown if they cancelled it because of the decision to stop making spring crossover movies, or if they were going to go ahead with it regardless, but backed out at the last minute.
Hacking the Evol-Driver reveals 3 additional unreleased Evolbottles - Tank, Lock, and Dinosaur. Tank and Lock were presumably scrapped on the grounds that, with the exception of the Rider Evolbottle, all of the Evolbottles Evol creates have corresponding Organic Fullbottles (and Tank and Lock are inorganic Fullbottles), and Dinosaur was likely scrapped because the corresponding Full Bottle was scrapped as well.
This is Yukari Taki's third appearance in the Kamen Rider franchise, as she previously played unrelated characters in one of the Kamen Rider W movies and an episode of Kamen Rider Ghost, respectively. Similarly, Akaso Eiji (Ryuga) had a prominent role in the second season of Kamen Rider Amazons.
And then there's Akira Hamada (Juzaburo Namba) who previously portrayed a minor character in Kamen Rider OOO, though actually made his first appearance in a Kamen Rider series all the way back in Kamen Rider Stronger as the villain Mr. Titan.
With the Super Hero Time block being moved, this will be the first series since the revival to not start at 8:00 after its sister Super Sentai series, instead airing at 9:00 before its Sentai sister series.
This is also the last series to have a fully televised run during the Heisei period, due to Emperor Akihito intending to abdicate the throne to his son, Prince Naruhito, thus beginning a new era in Japan effective from April 2019. The last series to air at the end of an era in Japan was Kamen Rider BLACK RX, although in that case, it finished its airing after the changing in erasnote since unlike Akihito, Emperor Hirohito died while in office during the airing of Black RX.
Aside from the aforementioned two examples, Build is the first series:
Since OOO not to cross over with its Super Hero Time Partner, either in one of the Super Hero Taisen movies or a TV special, after Fourze established the yearly streak.
Since Double not to have any sort of Spring movie attached to it.
Since the inception of the Spring movie slot with Den-O & Kiva: Climax Deka not to have A. the non-attached Spring movie premiering during its run be a Den-O movie (Amazons got the honor this time) and B. one of its Riders cameo in that movie to compensate (assuming one counts the Cho Den-O Trilogy during Double's run as one movie).
Since Ghost not to have a Super Hero Taisen movie attached to it.
Since Decade to use "Form" for the name of the various rider forms, instead of using a unique term such as States or Combo.
Since the start of the franchise to have its opening performed by a non-Native Japanese singer.
Since Gaim not to have the succeeding Rider make an Early-Bird Cameo in person in the show's final TV episodes. Instead, a reverse scenario occurs where Sento and Ryuga appear in their succeeding Rider's first two episodes to immediately establish that series as a Crisis Crossover.