I just noticed this while watching the "Cake Song" from the movie! I'm analyzing the verses. Sayaka:
Sayaka is the raspberry. I couldn't find much information here, because I can't think of anything for the raspberry to represent.
She says "the cake is red" which isn't really a subtle reference to anything, just Sayaka singing about Kyoko.
Kyoko is the apple. I don't think of anything here either, though.
She says "the cake loves Bebe", and Mami loves Bebe.
This is where it gets interesting. Mami is the cheese. Does this sound familiar? Yes, the witch that ate Mami, Charlotte, loves cheese!! Wow, so that's why she was eaten.
Then, she says the cake goes in circles. I think this is interesting, because Homura travels in time, infinitely, like a circle. This is really the only connection I could make here, is that Homura travels time infinitely, as a circle.
Homura is a pumpkin. Nothing here.
She says the cake is sweet. Madoka! Madoka's character is a sweet girl.
Ok, so Madoka is the melon.
"When the melon breaks, it creates a sweet dream"
Madoka = Melon
Melon Breaks = Madoka's Sacrifice
Sweet Dream = Universe where no witches are from magical girls
I think this song was meant to represent all the magical girls in a way that made sense. I like it that way.