The Alchemy Murder Case File 3 - S1-E8
Revealing mistake: The setup of the story is the usual; characters forced to coop together at a secluded location, they can't contact the outside world and one of them is a killer. In this case, they are on an island and the only radio they had been on the boat that someone set on fire. However, when one of the suspects shows Kindaichi a photo from their smartphone, the screen shows that they have an active 3G connection. (00:08:00)