Oh Brother Where Art Thou? is not only allegorical, but also a farcical comedy. Please consider how it reflects many commonly-held and very real beliefs about the South?
The eNotes/Wikipedia page about the theatrical farce defines it as follows:
In theatre, a farce is a comedy which aims to entertain the audience by means of unlikely, extravagant, and improbable situations.
The film Oh Brother Where Art Thou? does fit into the category of the farce specifically with regard to its portrayal of various aspects of the depression era south.
The film reflects on the racist notion that the people of certain areas of the south were simple and easily led by those who could charm them with rhetoric.
The film is filled with situation after situation where simple minded characters are bamboozled by people who may not know more than them, but who can turn a phrase and speak convincingly. Everett convinces his two less sophisticated companions, Pete and Delmar, to break out of jail and search for a make-believe treasure. Everyone in the party is tricked by the smooth talking, cycloptic bible salesman, Big Dan. In fact, Everett doesn’t even realize that anything is wrong even after he has attacked Delmar and is swinging a club at his head.
Now, part of what is so wonderful about a farce is that it is so extreme that it points out the ridiculousness in the beliefs that it is depicting. It can be argued that the film makers were indeed trying to show the ridiculousness of the racist belief that people from the deep south are all either dim witted or cruel and manipulative.
The film also reflects on the influence of white supremacist societies like the Ku Klux Klan in the old south. The KKK is a dangerously racist group and a force that causes the main characters a great deal of trouble in the film. However, at the same time, they are made to look ridiculous. We see them at a rally where they are singing ridiculous chants. At one point you can hear them say “Eeny, meeny, miny, moe” as in “catch a tiger by the tow.” At the same time, they are doing a line dance that would make more sense at a cheerleader convention. I also have to mention that in this same scene, the KKK characters also brought along the little man that works for the politician Stokes, and he has his own cute little Klansman outfit. However, after all of this, the rally still has a threatening aspect because the viewers know the history of the group, their creepy white costumes, and their racist and violent belief system.
Finally, the town collectively decides that Stokes, who admits to being the head of the KKK rally, is a bad guy, and they run him out on a rail. However, in an additional farcical twist, the real reason the town turns on Stokes is because he publicly shunned the Soggy Bottom Boys, a music group the town loves, not because he’s a violent, racist, bigot.
In writing about this topic I realized how gutsy the Coen brothers were to make this film with all the racist undertones; but overall it provided a modern commentary on the way many people view some very sensitive issues concerning the deep south of the depression era.