#46 has a Monster of the Week that summons manga characters to battle out heroes. The most fearsome of them is played by Yoshinori Okamoto, veteran suit actor usually in the role of The Dragon (eg. Biohunter Silva), now in a Dragon-esque role to the monster. (This is itself a Call Back to the first couple of episodes, as he also played the Original Kirigakure Saizou. Then joke then becomes Saizou getting his ass kicked by his still-unimpressed ancestor.)
Dawson Casting: Slightly inverted. Satomi Hirose, playing Tsuruhime, was not yet 14 when filming began. When Tsuruhime is shown celebrating her birthday onscreen mid-series, her birthday cake can be seen holding 16 candles.