My “field correspondent” tells me that the Canadian Pacific Railroad used Milan, MI as a stopover spot on this particular trivia night, which was more crowded than usual. This is not the first time such localized events have affected attendance on trivia nights at this place. In July, a cycling group used Original Gravity as a stopover on a trip, which just happened to be on a night where the AC at OG was not working very well (though it did kick in later). Plus some of the cyclists were a tad bit…ripe.
Answers will be revealed in the comments below.