Most of the girls are users of improbable weapons, but then, we have Rumi Nanase, wielding a wooden kendo sword. Why such weapon in particular? Well, it's a reference to her being part of a kendo club at her old school in ONE ~ To The Radiant Season, before she was transferred and forced to give it up.
Among the improbable weapons which may not be so improbable after all, we have Mizuka's schoolbag and cello (to reflect her musical taste), Mio's notebook (Which she uses to communicate), Ayu's winged backpack (A possible reference to the Spoiler Opening of Kanon, the 2002 anime, although that would be more of a Hilarious in Hindsight as EFZ was released in november 2001), sleepy Nayuki with a Keropi doll, Mai's ghost partner with a bunny-eared headband, sweet and cheerful Sayuri with a magical shape-changing wand, etc.
When Misuzu calls Yukito, what actually happens is that her crow partner Sora materializes as Yukito, which makes sense, since this is what happened in AIR, only reversed.
Fridge Horror: One of Akiko's supers has her catching a car speeding towards her with one hand, and slamming it against her opponent. Sure, the move looks cool but... What happened to the driver!? Did he/she escape in time? Or disppeared just as the car exploded?
If Misaki is blind, and Nayuki is asleep, how can they fight? Well it's not uncommom hearing about heroes who, while blind, can also be powerful fighters, such as Dare Devil, Kenshi, Toph, the guy from Blind Fury, etc. And there's also the ability to sense energy, so, why not? Also, in Kinnikuman, King Muscle and Kid Muscle developed something similar to a "fighting while asleep" technique, due to them sleeping in the same bed. So, if Nayuki's style with kicks is pretty awesome for itself, seeing her fighting while asleep is really impressive.
As mentioned in the main page, Makoto uses a gun in battle, and can fire it in front of her opponent, but it counts as a melee attack. Any reason for that other than gameplay?
And then we have some weapons that could be quite implausible: Akane's hair, Ikumi with blood, Makoto with her gun and other gadgets, Mishio's spear, and Kano's Magic Staffnote Although this one may not be that implausible, as it's a reflection of her wanting to perform magic in AIR.
Mai fights with iaijutsu, even though her sword is not a katana, so it's quite impressive.
So, Why does Nayuki (Awake) fight only with kicks? Yeah, yeah... As a reflection of her being captain of her school's track team... but, can't help but think there's something else. Actually there is, it's because Kaori, her best friend, had previously taken all the punching; Kaori had previously debuted in the Bad Moon Edition, and awake Nayuki appeared in Memorial.
So, how potent is actually Akiko's jam? In Kanon it was already bad enough, but in EFZ the girls are powerful enough to hold their own in wonderful duels, and despite that, a single taste of the jam is enough to knock them cold! Well, just because your body is tougher, faster, more agile, etc, doesn't mean your palate will also be tougher, does it? An it's Played for Laughs anyway.
In AIR, Kano wears her yellow ribbon on her right wrist because she believes it will grant her magical powers; in EFZ, despite her being a strong fighter and powerful user of elemental magic, she still wears the ribbon.
Game-Breaker: Kanna, simply Kanna: Her attacks have huge range and priority, and she wasn't nerfed for the multiplayer, which means players can abuse her high-priority attacks and damage outputs, so she's normally banned from high-level play. Fighting style-wise, she's like a combination of Justice and Dizzy, both from Guilty Gear.
The game has a cast of 23 playable characters, distributed in an 8x3 grid, with the second place of the last row reserved for the random select. Several years later, comes Arcana Heart 3: LOVE MAX!!!!!, another all-female Fighting Game, which use the exact same distribution for its roster.
In this game, Ayu grows wings behind her to fight; later in the 2002 anime version of Kanon, she's seen with pink wings during the Spoiler Opening.
Memetic Mutation: The Sayurispin, thanks to Sayuri being graduated from Rugal's school. Explanation Sayuri's Final Memory, called "Magical On-Stage", is based on Rugal's Dead End Screamer from '98 (which was the base for the "You Spin Me Right Round" meme), and it spanned several imitators, among them, sweet and innocent Sayuri Kurata.
Moe: Well, it's a Fighting Game with cute and adorable girls, masters of quirky fighting styles, so everyone counts to varying degrees. Special mention to Mayu and Mio for the ONE side, Sayuri and Nayuki for the Kanon side, and Misuzu and Kano for the AIR side.
Pop-Cultural Osmosis: A number of players had interest in AIR, Kanon, One and Moon, simply because of the characters' appearance here. Note that the last novel doesn't even have a TV Tropes page - that's how obscure they are.
That One Boss: Say what you want about Kanna, at least she goes mild on you at difficulties 1 and 2; Unknown, on the other hand, can be a headache at level 2: fast attacks, high priority, and a tendency of filling the screen with energy orbs and vertical lasers will keep you occupied for a time.