Blood Pool Hall Murder Case File 2 - S2-E6
Stupidity: Even assuming that running in flipflops down the gravel road would give the culprit the required advantage over Kenmochi and Kindaichi, the culprit still had to run the elaborate setup in an absurdly short amount of time without leaving behind a single piece of gravel or wet stain (he was elbow deep in water) and hope nobody would set foot in the courtyard during the commotion.