Ancient Astronauts: Doubly Subverted: After hearing about the hypothesis, minus goes back in time to try to meet the aliens. She doesn't find any... but at the end of the strip it is revealed that yes, aliens were responsible for the human race. She just didn't go far enough back in time.
Apocalypse How: Quite a few, but most famously the one that actually stuck, wherein minus resurrected the entire population of Earth, past and present, human and otherwise. It was crowded, to put it mildly.
Characterization Marches On: Despite, as can be told by most of the rest of this page, having a reputation for being dangerous, in truth, all things considered, minus' stops doing more negative things very quickly - by halfway through the comic she's almost entirely neutral: only doing negative things out of naivete rather than intentionally doing them, and she often adds things to her some of the less positive things she caused to make them bittersweet or even good. She never stops callously making synthetic sentient beings, however.
Chekhov's Gunman: The aliens. They first appear as the inhabitants of a random planet that minus visits on a lark. At the very end of the comic, it turns out that those same aliens were responsible for the evolution of humans.
Deus ex Machina: an in-universe version in minus herself, who tends to solve any problems or requests with a somewhat tangential application of her powers. Anyone who doesn't know about minus is usually some form of terrified or curious at the seemingly illogical and irrational things that occur around her (that tend to really be... well... illogical).
Kids Are Cruel: minus doesn't generally doesn't recognize the consequences of their actions until they're presented to her, if they ever are at all. This leads to a lot of Disproportionate Retribution such as turning a man into a balloon and letting him pop, or moments like the creation of a miniature civilization in her tub only to destroy it when bathtime ends.
Laser-Guided Karma: quite often happens when people get on the wrong side of minus. Sometimes subverted given her general lack of moral responsibility and the resultant Fridge Horror, like the balloon-seller's fate.
It's implied that these are future generations of dead people (so I guess ghosts can have kids and grow up). They never had legs.
Shout-Out: Various references to anime here. In order of lines, the immortal who wants to be human is from Soul Hunter, the second one sounds vaguely like a quote about immortality from Galaxy Express 999, the one about the witch giving up her powers is Ojamajo Doremi, and the quote about everything coming easy sounds similar to a lament made in Magic User's Club by Takeo's gay friend.
The dishman who was out dojo-hunting obviously battled a practitioner of Panzerkunst.
The Slow Path: #25 and #26. Slight subversion as she wouldn't make it back at all; minus brings her back in her old age to say good bye.
Silence Is Golden: While there are a few strips that have talking in it, many strips are pantomime.
Sociopathic Hero: minus, in as much as all children are kind of sociopathic. The strips are full of people whose lives she has ruined or casually tormented over a minor slight or just because she was playing around.
What Could Have Been: Strip #10 was the first one actually drawn, and at the time the creator had not yet decided whether minus would actually be all-powerful or just a shape-shifter. If he had chosen differently, the comic would have turned out very different.