The Campground 'Bizarre' Case - S1-E17
Deliberate mistake: The evidence that proves Kindaichi's alibi is the store receipt detailing the time of his purchase. Notice that the year is recorded too, but it reads "20XY." (00:12:40)
Inspector Kenmochi the Murderer File 3 - S1-E21
Audio problem: Kindaichi is listening to the recording of the phone call a couple times over; however he does not listen to it in a loop, but rather the file shows up as lasting 52 seconds, with the call being just a handful of seconds. On top of that, when he listens to it again in front of the building, the timestamps don't match.