Despite having no plugins installed through wordpress, I did have retina.min.js being enqueued in my functions.php file from the template I downloaded.
Retina.min.js (source: http://imulus.github.io/retinajs/) looks for high resolution versions (denoted with suffix @2x right before the extension) of each image in your site and attempts to replace them if any are found. Since I did not plan on using this feature for the time being, I commented it out of my functions.php file and I now have a clean console.