The Case of the Fanciful Frail - S9-E24
Other mistake: Park Milgrave finds a small chest full of realistic counterfeit money in Bruce Strickland's apartment. (Counterfeit money was not used for this scene. The chest actually contained three stacks of dollar-sized paper with a real bill on the top of each one.) Milgrave dumps the money into a metal urn and lights it on fire but the money he dumps out is play money, which does not look even remotely like real money.