Sawtooth was modeled after Dirk's Bro, which is why Dirk will never beat him in a rap-off.
Aradia was curvy, plus-sized, and generally gorgeous... But when Equius built Aradiabot, he made her skinny and closer to his standard of beauty. Needless to say, Aradia herself- who loved the way she looked- wasn't pleased and went back to her usual appearance when she got her tiger.
Dirk's robots and Hal all talk on a "secure" communication channel. It's actually pretty easily hacked and the other robots will occasionally pop in just to lurk or mess with everyone's heads.
Cal's thoughts