Only Phantom and Crypt Dragons appear in this track. It's possible that it could be reference to something like Chilling Chase having only Acid Dragons possibly to reference the Alien movie.
Uh...really...? Acid Dragons have never, NEVER turned up in my Chilling Chase...it's always been dragons picked by the usual algorithm that the game uses to pick opponents: Strongest (perfect match, often first/second place) at the top, second/third place (one affinity) below you, and horribly unprepared (often last, no affinities) at the bottom. I've seen one or two dark-element dragons in Chilling Chase, and even some Brass Dragons, but no Xenomorphs. Maybe it's because I'm not high-enough-level to breed them...?
this racetrack has the same name as one of the competition things in Whitbee’s candy bash IV which also had the elements cold and earth which match the ghost, spirit and spectre dragons. Maybe that’s why the dragons are always crypt or phantom. (See the similarity)