Shitty Movie Detail: Parasite

Ki-jung sitting on the toilet surrounded by a sea of sewage.
FT, Fartiste Theater's frankenthing mascot.
FT, Fartiste Theater’s frankenthing mascot.

During the heavy rains, the Kim family’s half-basement apartment floods. This flooding causes the sewers to back up, which in turn sends human effluent spraying out of the turlet. This, quite literally, is a shitty movie detail.

Furthermore, as the eponymous title suggests, there was at least one parasite in said sewage.