When filming the scene where Buford "Mad Dog" Tannen tries to lynch Marty, Michael J. Fox was accidentally hanged, rendering him unconscious for a short time. He records this in his autobiography "Lucky Man" (2002).
Clint Eastwood was asked for permission about his name being used for Marty in the film. He consented and was said to be tickled by the homage.
Marty uses a "Frisbie's" pie plate to knock a gun out of Mad Dog's hand. In 1871, the Frisbie Pie Company started in Connecticut. Their pie pans were thrown on the campus of Yale, and this eventually led to the invention of Frisbees. This is another example of Marty introducing something into the timeline earlier than its official invention, and thus potentially giving the original inventors the idea to make them; in Back to the Future (1985), he turned a soapbox cart into a prototype skateboard, and unknowingly gave Chuck Berry the inspiration for the song 'Johnny B. Goode'.
According to the book "Billy Gibbons: Rock & Roll Gearhead," ZZ Top was hanging around the set, and was asked to be the town band. During one take, the camera broke. While waiting for the camera to be repaired, Michael J. Fox asked if they would play "Hey Good Lookin'" which they did. Afterwards, more requests were played. Two hours later, someone inquired if the camera had been repaired. Robert Zemeckis replied that it had been fixed for quite a while, he just didn't want to stop the party that had evolved.
Tom Wilson, who plays Buford "Mad Dog" Tannen, performed all of his horse riding stunts himself. He also did the trick where he lassoes Marty just before he meets Doc in 1885.
ZZ Top: One of the film's composing bands has a cameo as the band in 1885, playing a variation of "Doubleback."
Robert Zemeckis: [citation] When Marty walks along the railroad tracks and finally reaches the town, he comes to the railway station. Then he walks into the town, while the camera slowly rises up above the station and finally shows Marty at a long distance walking into the town. This scene is shot exactly the same way as the scene in Once Upon a Time in the West (1968) when Jill arrives at the station.