12 billion yen incident
References to an infamous real-life incident involving Gold Ship (the racehorse) causing betting 'losses' of approximately twelve billion yen.
The actual incident happened at the 2015 Takarazuka Kinen, where Gold Ship was the guaranteed favorite to win. Then Gold Ship decided to randomly* rear up when the race started (holding that pose for some time), turning some twelve billion yen worth of bets into smoke.
(*Angered by a horse in an adjacent stall, according to some accounts.)
The Umamusume Gold Ship is sometimes drawn in scenes or with lines alluding to the above incident, as a reference to her real-life counterpart. The Anime version of Umamusume also made a reference to the incident in the first OVA episode, complete with Hosoe Junko (commentator) screaming as she did in the broadcast of the real life version.