Some of the more "sensitive" viewers, who forget this was made in 1931 and such things were out of the ordinary, will feel uneasy when Stan and Ollie are wearing blackface. They're wearing it to HIDE from prison guards, NOT to offend. Similarly, when going along with their disguise, Stan calls Ollie "Sambo", not to offend, but because it was the first 'black' name he could think of.
The ending prison riot is intense, but plenty of guns going off...but nobody is shot.