I dont really see anything you could be worried about, unless your talking about the vent??? In that case all snakes have them, maybe someone with more annie experience will chime in.
im talking about that dark brown spot, and i have no clue what it is. i just want to make sure its nothing thats gonna randomly kill my snake or something.
Keep in mind I have no experience with anaconda's, but what i see is part of the snakes pattern. I dont see anything i would be worried about. Lets see a pic of the entire snake