I actually haven't heard this theory. Perhaps.
the flying heads symbolize rape they are trying to fly away but they keep on getting pulled in by the gravitational force generated by the collective theories involving mado getting raped
Maybe she saw a decapitated head fly through the air and then roll off to someplace during the traffic accident. If you subscribe to the traffic accident theories involving monoko, stoplight effect, dead body man, and other in-game references.
They fit on those pregnant dick monster looking things.