Double is laden with homages to the shows that came before it, particularly Showa-era Rider.
- Thanks to the two-men-into-one Rider System, we have the first Kamen Rider to use both the best-known methods of donning the Rider Belt: Shotaro wears it manually (first done by Riderman and Faiz), and the belt materializes around Philip (started by the original Kamen Rider).
- With the introduction of the Fang Memory, it plays homage to another relatively popular Belt gimmick: The Fang Memory is capable of attacking enemies on its own, briefly stunning them, a trait first introduced in Kamen Rider Kabuto with the Zecters and later also used with Kivat in Kamen Rider Kiva.
- Speaking of Fang, activating the Maximum Drive requires Double to hit the horn 3 times as done by Kabuto.
- It should also be noted that Double isn't exactly the first Rider to share a body as a gimmick. All the colored halves of Double are colored similarly to the Taros, Deneb and Sieg, with the purple areas on Joker corresponding to Ryuta, and Metal silver representing Teddy. And Double uses his hoverbike for the first time against an aquatic monster much like Rod Form used the Radome in his debut.
- Crosses into Harsher in Hindsight with the Liar Dopant, who interprets Kintaros' Catchphrase AND use of actual papers a little differently.
- And Shotaro going into full hero mode, at the potential risk of his own life, seems to also homage Kintaros taking over as Den-O at the sight of a person crying.
- Speaking of which, Akiko inherited Momotaros' shouting fits (her reaction to Xtreme Form even mirrors Momo's reaction to getting Climax Form).(In ep. 3) "I'm pissed!...part two."
- And CycloneJoker form carries notable elements of Kamen Rider-1 (Hongo Takeshi)'s design: metallic green and black as main colors, red eyes, the scarf, and double silver stripes (only down the middle and not the sleeves and legs.) In a similar vein, HeatMetal colors are similar to Kamen Rider X (who incidentally was the first Rider to wield a rod). Also, LunaTrigger has the colors associated with the alternate forms of Kamen Rider BLACK RX (blue for Prince of Wrath/Biorider, yellow for Prince of Sorrow/Roborider). It should be noted that Roborider's weapon was a gun and Biorider's ability to become a viscous liquid predates the Luna half's bizarre flexibility.
- It's probably worth noting here that Kamen Rider-2 (Hayato Ichimonji) also carried those colors. Both of them are usually referred to as: wait for it: Double Riders.
- Cyclone form is the only one with a scarf. Fitting, considering that the original three Riders were powered by wind and that Cyclone was the name of the Cool Bikes used by the original Double Riders.
- The spinning circle on CycloneJoker Xtreme's belt references the one on the very first Kamen Rider's belt, Typhoon. Not only does it look similar, but it's even named Xtyphoon. The fact that Xtreme Memory takes the form of a bird also references the eagle motif on Shocker belt buckles.
- The Training from Hell that Shroud puts Terui Ryuu through in ep. 36 is something that Ichigo and most Showa Riders would already be familiar with, courtesy of Tachibana Tobei.
- Perhaps the Masquerade Dopants could also count in as upgraded and glorified Shocker mooks (in suits, no less!) They also get scramblers in Forever A to Z.
- Double's asymetrical color scheme is reminscent of Kikaider, another Ishinomori series. And when in HeatTrigger form, he has the exact same colors as Kikaider 01.
- In "The Girl...A", a small girl carries a soft toy that resembles Kamen Rider Knight.
- The "Joker Extreme" kick order is quite reminding of the leg position of the sideway Rider Kicks.
- Skull is pretty clearly an homage to another Ishinomori creation serving as a proto-Kamen Rider of sorts, the Skull Man.
- Alternatively, it could be a Shout-Out to the manga Kamen Rider Spirits, namely to Interpol agent Taki Kazuya, who pretty successfully attempts to become a Kamen Rider himself despite lacking any kind of augmentation. And to compensate for his lack of cybernetics, Skull Rider uses guns.
- Similarly, Accel carries many visual similarities to an Ishinomori tokusatsu hero called Kaiketsu Zubat.
- The Arms Dopant not only borrows the Trial Undead's pastiche of mimicking Kamen Riders, but some design aspects as well (skull-like features and cybernetics).
- Watcherman is a very subtle one: His appearance is based on Ishinomori.
- There's also a parallel between the main characters of Double and another detective-themed Toei tokusatsu:
- Shotaro is Ban (impulsive hero) and Hoji (obsessed with being a pro/hardboiled, likes to act cool).
- Philip is Sen (Bunny-Ears Lawyer, The Smart Guy) and Jasmine (supernatural powers, formerly saved by their mentor).
- Akiko is Umeko (childish, The Napoleon).
- Terui is Tetsu (bike-themed Sixth Ranger, joins the story due to vengeance on his family's murderer).
- Sokichi is Doggy (Mentor character with a darker themed transformation.)
- From Double Forever: A to Z, Kamen Rider Eternal not only draws upon elements of Oni design (banded armor instead of chestplates, and two-colored flaming motif), but is colored the same as Oni-form Kiriya.
- Before that though, Bird Dopant can be heard repeating the phrase "onii-san, kochira" (normally heard from Douji and Hime) in ep. 18.
- When we first meet Dr Isaka, he's in a tuxedo and bowler hat, playing a piano - referencing the old man who'd been forgotten by everyone except his only friend, the young piano genius who'd been in a coma for some time, causing the old man to lose his place in time from Kamen Rider Den-O.
- The Hopper Dopant, who fights exclusively using kicks not unlike Kamen Rider Kick Hopper (especially with the sparks from the heels just like Yaguruma and his spurs)
- Who in turn was a Shout-Out to the original Kamen Rider 1.
- In Kamen Rider: The First Hongo Takeshi/Kamen Rider 1 ws referred to as Hopper.
- Furthermore in human form, she uses boots with stun gun heels - just like Taki Kazuya.
- Mikio Jinno is an Expy of Okubo Daisuke, the ORE Journal chief from Kamen Rider Ryuki.
- Kamen Rider Joker looks remarkably similar to Kamen Rider BLACK, and even strikes the same pose as him.
- This can count as an Homage, as Renn Kiriyama/Shotaro has stated he is a huge fan of Kamen Rider BLACK.
- The Utopia Dopant rather resembles Kamen Rider Gaoh, including the way the trinket is dropped to start the transformation
- And he uses Garren's backflipping-drop kick Rider Kick during the final battle, where it's countered by Double's Double Prism Xtreme.
- In the crossover movie set with Kamen Rider OOO, we are shown Soukichi Narumi's first case as Kamen Rider Skull. Who does he fight? The Spider and Bat Dopants.
- In A to Z: The Gaia Memory of Fate, several sound effects first used in Kamen Rider are used a couple times.
- Speaking of which, the sound of the Ongeki drum can be heard during the Jidaigeki dream in "The Nightmarish H" (the moment Terui Ryuu shows up).
- The Weather Dopant describing the sight of a Kamen Rider sleeping in the open as 'surreal'...did he catch the ED for Kamen Rider Kuuga?
- The net-exclusive comedy shorts released alongside Double Forever manage two Shout Outs to previous Kamen Rider shows. When discussing the Feudal Japan Memories from the Nightmare arc, Jinno suggests that the Feudal version of Fang would be "Kiba", followed by saying "Kivatte ikuze!". Makura interrupts, saying, "That's from that Kouji Seto show!" In another short, Shroud tells Akiko that they're going to go on a journey to learn as much as they can about all the Riders; Akiko protests "But it's not like I'm Decade or anything!"
- Accel has two Super Modes, one which gives super speed, and the other which allows him to fly.
- Also from W Returns: Accel, the Commander Dopant's Mooks have Zectrooper body armor, which had previously been recycled for the Lion Imagin's minions.
- The location of the final battle is Kazami Quarry, which may serve as a Lampshade Hanging on the fact that V3 and Accel have similar backstories (losing their parents and little sister to a Kaijin).
