Acting for Two: Eric Bauza voices Dark Opal, Citrina, and the Pegacorn. He also voices the tree in episode 3.
Also in episode 3, Sophie Oda, who voices Amy/Amethyst, does the talking flowers and lily pads.
Name's the Same: No relation to Cartoon Network's otherAmethyst. Although both series love their Rock Theme Naming, so there was bound to be some overlap (both series also share the names Opal, Sardonyx, Sapphire, Topaz and Diamond).
Screwed by the Network: Was delayed past it's intended premiere date for an whole year and, despite favorable reviews and reception, DC passed on making it into a full-fledged series in favor of focusing on the usual money maker.