404 on some PNG files

When pulling up the console I am noticing some 404 errors on a few PNG files. Yslow and Google Insight also reports them. They are the following:

GET http://santacruzsurvivors.com/wp-content/themes/tank/images/content/top-r.png 404 (Not Found) santacruzsurvivors.com:265
GET http://santacruzsurvivors.com/wp-content/themes/tank/images/content/bottom-r.png 404 (Not Found) santacruzsurvivors.com:485
GET http://santacruzsurvivors.com/wp-content/themes/tank/images/slide-left.png 404 (Not Found) santacruzsurvivors.com:209
GET http://santacruzsurvivors.com/wp-content/themes/tank/images/slide-right.png 404 (Not Found) 

Should I create 1x1px images and place them in so they are no longer 404, or should I remove the reference to these PNG in the code? Where would that code be found?

Thanks

For now I have made 1x1px images with the above names, If there is a better way let me know.