Good question and good point! I would say that we would follow the equator along the latitude, and for people who want to add facts about countries, it can be when we pass the longitude that their country is on. That way we will be able to do all countries. 
As for the starting location, let’s check with @mrnoone !
298 (community total) + 13 (my reviews) = 311
311 (community total) + 69(my reviews) = 380
380 (community total) + 32 (my reviews) = 412
412 (community total) + 21 (my reviews = 433
433 (community total) + 10 (my reviews) = 443
I really like the whole idea. Motivates me to review more and contribute to the goal. Plus a shiny badge! Next time we go to the Moon? 
443 (community total) + 61 (my reviews) = 504
504 (community total) + 40 (my reviews) = 544
544 (community total) + 35 (my reviews) = 579
579 (C) + 19 (part 2 of today’s reviews) = 598
598 (community total) + 60 (4th review session, second this race) = 658
658 (community total) + 24 (my reviews) = 682
682 (community total) + 12 (my reviews) = 694
694 (community total) + 123 (my reviews) = 817
817 (c) + 43 (mine) = 860
860 (community total) + 11 (my reviews) = 871
871 (community total) + 10 (my reviews) = 881
881 (community total) + 42 (my reviews) = 923
Time to go around the world!
923 (community total) + 16 (my reviews) = 939
939 (community total) + 10 (2nd batch for today) = 949