Dave, I hate to say this... but in the real Modern Pentathlon, the competition is all in one day, and the competitors have no choice in their mounts (they are handed out randomly). So, even though I love the plot twist with Oso, it couldn't really happen IRL.
Contestants get points for each of the first four events in the Pentathlon - shooting (10-meter air pistol), fencing (epee saber), swimming (200-meter freestyle), and riding (show jumping). The last event, running (3,000-meter cross-country race), is a staggered start, with the contestant with the most points after four events running first - and each remaining competitor starting at intervals in relation to their point totals.
Yeah, I'm a complete nerd over this, but I'd have to say Baron du Coubertin was even more of a nerd.
"Character is what you are in the dark." - D.L. Moody