After over ten years in the movie business making comedy shorts, Roscoe 'Fatty' Arbuckle finally went over to features with this movie.
This film was the first of over 300 feature-length Westerns shot in Lone Pine, California.
Buster Keaton appears in at least 2 scenes: First at 0:11:40 as Wallace Beery and Indian band stop; Buster is dressed as an Indian, wearing a patterned shirt with dark background, appearing right behind Wallace. Second at 1:05:00 with Buster as the Indian who has the knife shot out of his hand by Fatty just as he attempts to scalp the fallen calvary soldier. Buster flees, only to be killed by Fatty and Buster then tumbles head over heels, downhill, perhaps inspiring his later feature film spectacular falling rock/tumbling stunt in the 1925 "Seven Chances."
At the time "The Round-Up" was filmed, Fatty Arbuckle was being paid $5,000 a week. That was quite a sum in 1920, when one could live very well on less than $5000 a year.
Buster Keaton, who plays a bit part in the film, was paid $7.50 for this movie. Once paid, Buster put his 'salary' in a frame and hung it in his office. Already famous at the time, he said he took the bit part role just for the fun of it.