Every exterior shot - and even some interiors at the unnamed college campus - was accomplished largely guerrilla-style in Olympia, WA, with no permits and usually no crew besides director/actor Augustine Dalton, actor Gabe Hall and usually one or both of the two's girlfriends on sound duty.
The villain wearing a Joe Biden mask was a largely serendipitous choice; Augustine Dalton found it at a Halloween store at random and found it creepy enough to decide to form a character around it.