Episode 19: During the soccer match, Cure Diamond says arienai, too.
Episode 22: Ira and Mammo's Team attack looks like a near identical version of the Pretty Cure Marble Screw attack, only red and yellow fires instead of black and white thunders.
Episode 25: Cutie Madame's costume looks a lot like Cure Passion's. Of course, the real Cure Passion would not be happy that someone dressed almost like her was impersonating a costumed hero for her own selfish reasons...
Episode 27: Aguri wears a yukata with a butterfly motif. In the following episode, she wears a yukata with a rose motif. Both, butterflies and roses are Yes! Pretty Cure 5 themes.
Episode 30: Even though they did this before, Cure Heart and Cure Sword say "Precure Double Kick".
Cure Diamond says "arienai" again.
The new attack Lovely Force Reflection is basically Rosetta Reflection, but enhanced by Rosetta's three comrades. That happened before in the final episode of Yes! Pretty Cure 5 GO!GO! when the four Precures and Milky Rose enhanced Mint's Emerald Saucer.
Episode 33: Rosetta Reflection is broken in two halves? No problem. Throw them like Emerald Saucers.
Alice's flashback shows how she met Mana. Alice chased a butterfly and got somehow a Crash into Hello with Mana. Mana then rose her hand and the butterfly landed on her index finger. And Mana asked Alice if she likes butterflies. Does this remember you of Nozomi and Coco?