Nightmare Fuel: In #40, the evil plot du jour? Evil soap! You'll laugh until you find out what it does. At one point we're treated to the sight of a five-year-old getting melted and washed down the drain as a pulsating blob of red goo even as we still hear his voice begging for help. Now, obviously, since it's Masaru, he's going to get better, but that so doesn't help at the time.
Special Effects Failure: Most of the show holds up pretty well, but some of the fight scenes have Kazuya throwing around some really obvious dummies.
Granted, the past shows had some really odd-looking monsters here and there, but this show had their villains head in to some really, really, really weird directions.
The monsters' themes are pretty much chosen to make sure it goes this way. Almost all KR series have animal monsters, but once Terror Macrow, who uses animal monsters, goes down for good and is replaced by a group of five major villains, that gets replaced with themes like a ladder monster, an umbrella monster, or a soap monster. Some viewers find it refreshing to see them get more creative than just having the ten thousandth silly-string-shooting spider or chameleon impersonating this week's guest star, while others feel they should have stuck to tradition because it's hard to take the new designs seriously.