Kotaro's invention of an 'Ape Undead' raises the question of why there isn't an actual one. There are 53 Undead, but this is nowhere near enough to represent all creatures on Earth.
It takes 1 minute 48 seconds for the bombs' ten minute countdown to reach zero, although the sequence of events is clearly not meant to be in real time.
As Kotaro drives the Land Rover away from the hospital, the close up shot of him reveals the sound microphone hanging from the sun visor above his head.
For some reason, there is a strobe lighting rig at the back of the cave as Kazuma leaves Kotaro.
For some reason, the Flying Fish Orphenoch decided to shoot past Masato and Mari to kill a man in front of them and reveal itself rather than target them first.
As Mari tells her story about the fire, neither Takumi or Keitaro notice the lights in their apartment go off and a spotlight fall on Mari.
In the service station cafe, a close up shot shows Keitaro checking his phone for messages then closing the lid, but the following wide shot of him with Takumi and Mari shows him closing it again.
It appears that whetever Shinji did to stop the Rider battle, it would prove futile. Continuing to fight would prolong the fighting indefinately, yet destroying the Core Mirror did nothing, as the Riders and the Mirror World still existed.
Unlike Sakakibara, Ren's body did not dissolve in the Mirror World after he died.
Jun's fans apparently know that he is a Rider and of the Rider battle as he does not seem concerned about discussing the subject in front of them.
During the final battle, as all the Riders prepare their Final Vents, Zolda activates his, but at no point does his contract monster, Magnugiga, appear even though it is an integral part of Zolda's End of World attack.
As Asakura transformed in the prison cell, he was holding the Ohja card deck the wrong way around as he inserted it into the belt but the close up showed it positioned correctly.
Miho/Femme, Asakura/Ohja and Ren/Knight all initially mistake Ryuga and Dragblacker for Ryuki and Dragreder, despite the obvious colour and Visor voice differences.
Miho says that Shinji's stolen wallet contains only 10 yen in coins, some of which she spends at a vending machine. However, as they fight over the wallet, a shower of coins is thrown onto the floor.
The trailer for this episode, shown at the end of Episode 48, has Shiro saying "Only the final Kamen Rider gets to fight Odin", something which he does not say here.
Sanako remembers taking the death certificate from Reiko from a third person perspective (the flashback is not through her eyes). The flashback is not even the same as the scene as it was originally shown in the previous episode.
When Shinji drops the Ryuki Card Deck onto the hospital room floor, it lands with the dragon motif facing him and the bed, but when Yui arrives, it has turned to be facing her and the door.
The weather at Nihonland is extremely changeable. When Yui begins her ride on the merry-go-round, it is a bright day, but by the time she gets off, it has been raining with many puddles visible and a lot of mist. Shinji's hair also goes from dry and loose to wet and slicked back during his conversation with Ren.
Unusually for Japan, Kitaoka's BMW 525 is a left hand drive model.
Although Reiko and Shinji are supposed to be in non-stop elevators, both Gorou and Kitaoka manage to board the lifts in mid-journey.