As part of the promotion for the movie at the Comicon in San Diego, promoters threw a huge "Welcome" party open to the public, with barbecue, beer, skateboarding demos, and a wall where people could write "subjects" they'd like to study. Justin Long and other cast members mixed in with the crowd, to the point that you couldn't pick them out.
During the hot dog costume scene, Schrader mentions how James Garfield even wore the suit, though not a member of the fictional BKE fraternity in the movie James Garfield was in fact a member of the Delta Upsilon International Fraternity. Plus, the earliest possible date for the invention of hot dogs is 1870. James Garfield graduated from college in 1856 - fourteen years before hot dogs were supposed to have been invented.