Surrealism is characterized by unexpected juxtapositions of fact and the fantastic and non sequiturs.
Regarding the second half of Flannery O'Connor's short story, "A Good Man Is Hard to Find" there are some elements that can be interpreted as surrealistic. For instance, the Misfit's allusion to Jesus is certainly an odd juxtaposition of himself and Christ in his imagination:
"Jesus thrown everything off balance. It was the same case with Him as with me except He hadn't committed any crime and they could prove I had committed one because they had papers on me...."
The convict calls himself "The Misfit" because, he says,
"I can't make what all I done wrong fit what all I gone through in punishment."
Certainly, it seems grotesquely fantastic and non sequitur that the Misfit would just kill Bailey and his family so he can record his crime and see if it matches his reported crimes and record. That he would slaughter the grandmother's family because what he has done wrong does not "fit what all I gone through in punishment" seems unreal.
In addition, that grace is available from someone who is gruesome has an surrealistic tone to it. When, for example, the grandmother recognizes the Misfit as "one of my own children," there is the juxtaposition of the depravity of man with the grandmother's reception of grace in acknowledging her sinfulness.
Darkly humorous, but disturbing is the Mistfit's remark about the grandmother,
"She would have been a good woman....if it had been somebody there to shoot her every minute of her life."
This juxtaposition of grotesque humor with the recognition of the grandmother's redemption, indeed, suggests an element of surrealism.