Originally made for television in 1966, but released to theaters instead, before being shown on TV because of its violent content.
Aired on ABC-TV only seven months after it opened - the quickest turnaround from theatrical release to television premier at the time per a contemporary article in Daily Variety.
Based on the first novel by E.L. Doctorow, and the first of his novels to be filmed.
In the United Kingdom, this film did not appear until 1970, when it was shown in the lower half of a double-bill with (of all things) Antonioni's "Zabriskie Point". It was cut by twenty-five minutes and renamed "Killer On A Horse"; however, the full version of the film was shown, under its proper title, several years later on British television.