Man Behind the Man: Smart Brain is shown as truly being run by three guys seen as blurry faces on hologram screens. All of them are played by longtime TokuBig Bad voice actors who've been menacing Riders and Rangers since The '70s. (One of them is Goro Naya, which is really interesting, given the recent Word of God about every Naya-voiced "[Organization Name]'s Great Leader," no matter how different-looking from the last or or clearly dead by the end, being the same guy.)
Rhino Rampage: Variant: The movie-exclusive Elasmotherium Orphenoch rampages, with Kiba/Orga as one of its victims.
Surprisingly Good English: Leo/Kamen Rider Psyga, played by America-born Hongkong-based actor Peter Ho, speaks perfect English. According to legend his Japanese was so bad that the director told him to stick to English.
Zombie Apocalypse: This movie shows the scenario of what if the Orphenochs took over 99.9% of the world. (The answer is, it sucks to be a human in that world, but the Orphenoch majority lives pretty much like we do.)