In the back of one’s mind

If something is “in the back of one’s mind,” the person is aware of it, but it is not the main thing someone is thinking about. In the episode, there is one obvious option for dealing with the hippo problem in Colombia that is “in the back of my mind” while discussing the other options. The option to let people hunt the hippos is the option that I am aware of, or that is “in the back of my mind,” but this option is complicated due to backlash Colombia might get. One time when I forgot to pay a parking meter in the city, my car got towed. Now, whenever I go into the city, the possibility of my car getting towed is “in the back of my mind.” I’m not thinking about getting towed the entire time I’m in the city, but I am aware of it.