This reference to Mars could easily be a way to promote TSR's Warriors of Mars which also came out in 1974. It could also be a reference to the time when Gary Gygax ran adventures for his Greyhawk group (LGTSA) which took them to Barsoom.Some areas of land could be gates into other worlds, dimensions, times, or whatever. Mars is given in these rules, but some other fantastic world or setting could be equally as possible. This function is up to the referee, and what he wishes to do with it is necessarily limited by his other campaign work. (p24)
Gronan (Mike Mornard) talked about this adventure over at the OD&D forum:
@gronanofsimmerya wrote:I never went to Barsoom, but Ernie did, and Rob wanted to. There were some odd bits of science fiction (more "Sword And Planet," actually) in Greyhawk but it was a long time ago.@archersix wrote:I'm really enjoying reading this thread.
I've read that Gary referenced Barsoom in his Greyhawk dungeon. Did you ever experience any Mars themed adventures? Did you see any other old science fiction references? Buck Rogers or Flash Gordon? Any Cthulu stuff? Or anything else?
And there was a "Church of the Latter Day Great Old Ones," which we avoided like crazy.
Now, I guess the Oerth Solar System was later changed to adapt Greyspace to the Spelljammer setting, but could these stories and old references be used as background for a Greyhawk/Barsoom crossover adventure?