Cloud is drawn in a more Animesque style than the other main kids. He's half Asian.
Gunnerkrigg Court seems like an odd choice for a crossover, but wait: Sandra and Woo has mythical monsters such as mermaids and sasquatch, intelligent, talking animals, and animal gods—this is exactly what the world outside of GC would look like.
More than any other aspect of her pyromania, Larisa keeps emphasizing the fact that fire is beautiful and that she can't look at it enough. She knows that she's about to go blind.
Zoey winning the contest between herself and Sandra makes a lot of sense if you've done a bit of observation and a bit of Archive Binge on the character. Note the differences between Sandra and Zoey in this strip. Zoey, being a lesbian, would of course be comfortable with being intimate with other girls, hence her being able to put more passion into the kiss than Sandra, who was showing signs of nervousness. Also, note her posture: She gave Larissa the exact same kiss she gave Michelle a while ago. Also, when you consider the Tear Jerker moment Sandra unintentionally invoked by stopping the contest to smooch boys◊, this was also the author's way of throwing a bone for Zoey!
Larisa apparently has Wolfram Syndrome, which includes as the first symptoms loss of colour vision. The first thing she is likely to lose is the ability to paint.
The human god of this universe was previously just used for comedy in reference to the Raccoon Goddess' past. What does he do in his first appearance? Casually sign Sandra's death warrant solely to screw Cloud over. Let me repeat that: the human god sets up a child to die brutally so that Cloud, one of the nicest characters in the comic will turn into a ruthless crime lord over his heartbreak. When the devil is a nicer person than God, there's something wrong.