Act 0, notably sillier than the rest of the show, has some really golden moments.
The first meeting of Minako and Artemis has Minako wondering how a toy cat can talk, first guessing that he's a robot and then beginning to talk to him as if he's a parrot or mynah bird. Cut to Artemis suddenly dressed up as a mynah bird for absolutely no reason, happily repeating her phrases like a mynah bird... and then doing a "what the heck am I doing this for?!" double take.
Sailor V's first battle with a wanted criminal. Completely inexperienced, she spends the first half of the battle yelping and running away from the guy, but ends it by dropping a tree on his head.
Usagi and her friends Naru, Momoko and Kanami being inspired by Sailor V and cosplaying as Sailor Senshi. Naru, Momoko and Kanami call themselves "Sailor N," "Sailor M" and "Sailor K," while Usagi becomes "Sailor Rabbit," complete with bunny motif.
Usagi's disguise as Sailor Rabbit was the silliest, to the point that Naru called her out on that.
The 4 cops played by the same guys who played the Shittenou. They take the Shittenou's qualities and play them Up to Eleven.
In the series, Mamoru bragged he knew that Minako was Sailor Venus since the times of Sailor V. It's shown how it happened: Usagi, realizing she had forgot about Minako's new album being published that day, cried "Aino Minako" while looking in Sailor V's general direction, prompting the latter to freak out and blurt "How does she know?!" while in Tuxedo Kamen's hearing range. Made even funnier because both V and Tuxedo Kamen were hidden near each other but none had noticed the other until V freaked out...
When Usagi accidentally blurts out she's Sailor Moon and Mamoru pretending he didn't hear anything
Mamoru: Oh, a bird.
Usagi: Oh, grass.
Usagi wants to work on a unicorn costume for a contest, but she can't until her homework's finished. Shingo tells Ikuko that too much studying might make Usagi go crazy. Ikuko tells him that's nonsense and she's going to reward her daughter by giving her a snack. Meanwhile, Usagi has finished her homework and starts working on her costume. Ikuko walks in on her daughter prancing in front of a mirror dressed like a unicorn and chanting "Kupi! Kupi!" Ikuko breaks down crying, sure that her daughter has gone insane.
A rare moment of Minako showing a hint of the silliness she displays in other versions: In the Valentine's Day episode, she gives Artemis a box of chocolate — which turn out to be spring-loaded stuffed toy that startles him. The expressions on Artemis's plushy face pushes the moment from "kinda funny" to CMOF.
Artemis falls for the same trick again on Minako's final episode, with a more exaggerated reaction.
Also, in one occasion Rei and Minako were helping a priest caring for some stray dogs. Cue Rei bringing some food and other necessary items and Minako showing up at the same time with the same item Up to Eleven and smirking.
Usagi babysits a little girl, Hikari, who is in love with a boy who has a crush on Mamoru's girlfriend. Said girlfriend gives Usagi and Hikari candy. Hikari gives hers to a kid and she declares "I will not lose to that woman". After hearing this, Usagi hid her candy.
Usagi's mom is bugging her to get out of bed for school, and when ignored, she sits on her daughter. Usagi's squirming and cries for help and the look on Ami's face as she bears witness to the silliness is priceless.
The scene with Artemis cooking for the children in Act 46, with all the success you might expect a tiny plush cat to have in the kitchen — trying to lift a frying pan that's bigger than he is and accidentally smashing eggs against the floor. You have to give him points for effort, if not for style.
When Sailor Venus decided to apologize to Sailor Moon for her attempt at making her forget Mamoru by giving her tickets for her concert as Minako, Sailor Moon wondered where Venus found them. At which point Tuxedo Kamen deadpans that maybe it was because it was her concert and, realizing that Moon was the only one who didn't know that Sailor Venus and Minako Aino were the same person, brags he knew it since her times as Sailor V. Became Hilarious in Hindsight when Act 0 came out and we see he found out due Usagi accidentally making Sailor V blurting it out with him overhearing by chance.
The Pierrots attempted kidnapping of Minako in the Special Act. They quickly subdued her bodyguards while Minako complained about their weakness, then they had a massive Oh, Crap when they saw that Minako, while depowered, could still kick them into concrete hard enough to shatter it.
Every scene with the Fake Shitennou, including their faces when the real Shitennou arrived to kick their asses.
Mio's reaction at the Sailor Senshi recovering their powers just to kick her One-Winged Angel form.