The Foot were one of many Daredevil in-jokes Eastman and Laird made in their first issues. They're a reference to the villainous Hand ninjas Daredevil frequently fought. "Splinter" is likely a reference to his martial arts tutor Stick. And art depicting the fateful ooze spillage mimics a scene from the hero's origin story, even stating that the stuff blinded a bystander.
A lot of TMNT makes more sense to me now.