Hostiles and Calamities - S7-E11
Revealing mistake: When Frankie and Tanya visit Eugene while he's playing the video game, he refuses to give them the pills he made. They call him a coward then leave, and in the next closeup of Eugene's video game screen we can see his reflection, but the problem is his reflection is not backwards as it should be (note his shirt buttons, etc). (00:44:10)