Roy Kissin, who co-wrote the screenplay, competed in the Dipsea, if memory serves. He was an outstanding runner from Stanford, I believe. Other repeat race winners featured in the film were Darryl Beardall, who was a major character in the film, Sal Vasquez, who won the race seven times, and Russ Kiernan. Jenny Biddulph was also in it, in her early teens at the time. She is know better for being the co-creator, with her late husband, Brian Maxwell, of energy bars, namely Power Bars. The race is handicapped by age and sex, and she did very well, given a head start because of her young age and gender. Bill Bailey was a real radical activist from the '30s, as was Walter Stack, who was a longshoreman during the 1934 General Strike in San Francisco, and in his seventies, the president/impresario of the renowned Dolphin South End Running Club. The race has been held annually for over a century.
