For whatever reason, we hold our big parade in May - but it matches what you describe. Tailing along this year at the very rear was a group of red hats looking like complete idiots - clueless and tone deaf. Turns out they didn't want to pay the $129 entry fee (b/c "freedom"?) so they thought they were being clever - in their words "just walking along the parade route after it was over".
Could anything be more perfect than a group supporting T-rump trying to skirt the rules for their own gain? Even my 15-year old looked at them and muttered "idiots" under his breath...